diff --git a/include/nksip.hrl b/include/nksip.hrl
index e9d072ca..ae1b497f 100644
--- a/include/nksip.hrl
+++ b/include/nksip.hrl
@@ -134,14 +134,14 @@
     id :: nksip_sipmsg:id(),
     class :: {req, nksip:method()} | {resp, nksip:sip_code(), binary()},
     srv_id :: nkserver:id(),
-    dialog_id :: nksip_dialog_lib:id(),
-    ruri :: nksip:uri(),
+    dialog_id :: nksip_dialog_lib:id() | undefined,
+    ruri :: nksip:uri() | undefined,
     vias = [] :: [nksip:via()],
-    from :: {nksip:uri(), FromTag::binary()},
-    to :: {nksip:uri(), ToTag::binary()},
+    from :: {nksip:uri(), FromTag::binary()} | undefined,
+    to :: {nksip:uri(), ToTag::binary()} | undefined,
     call_id :: nksip:call_id(),
-    cseq :: {nksip:cseq(), nksip:method()},
-    forwards :: non_neg_integer(),
+    cseq :: {nksip:cseq(), nksip:method()} | undefined,
+    forwards :: non_neg_integer() | undefined,
     routes = [] :: [nksip:uri()],
     contacts = [] :: [nksip:uri()],
     content_type :: nksip:token() | undefined,
@@ -152,7 +152,7 @@
     headers = [] :: [nksip:header()],
     body = <<>> :: nksip:body(),
     to_tag_candidate = <<>> :: nksip:tag(),
-    nkport :: nkpacket:nkport(),
+    nkport :: nkpacket:nkport() | undefined,
     start :: nklib_util:l_timestamp(),
     meta = [] :: nksip:optslist()   % No current use
 }).
@@ -166,7 +166,7 @@
 }).
 
 -record(via, {
-    transp = udp :: nkpacket:transport(),
+    transp = udp :: nkpacket:transport() | binary(),
     domain = <<"invalid.invalid">> :: binary(),
     port = 0 :: inet:port_number(),
     opts = [] :: nksip:optslist()
@@ -175,33 +175,33 @@
 
 -record(invite, {
     status :: nksip_dialog:invite_status(),
-    answered :: nklib_util:timestamp(),
-    class :: uac | uas | proxy,
-    request :: nksip:request(),
-    response :: nksip:response(),
-    ack :: nksip:request(),
-    local_sdp :: nksip_sdp:sdp(),
-    remote_sdp :: nksip_sdp:sdp(),
-    media_started :: boolean(),
+    answered :: nklib_util:timestamp() | undefined,
+    class :: uac | uas | proxy | undefined,
+    request :: nksip:request() | undefined,
+    response :: nksip:response() | undefined,
+    ack :: nksip:request() | undefined,
+    local_sdp :: nksip_sdp:sdp() | undefined,
+    remote_sdp :: nksip_sdp:sdp() | undefined,
+    media_started :: boolean() | undefined,
     sdp_offer :: nksip_call_dialog:sdp_offer(),
     sdp_answer :: nksip_call_dialog:sdp_offer(),
-    timeout_timer :: reference(),
-    retrans_timer :: reference(),
-    next_retrans :: integer()
+    timeout_timer :: reference() | undefined,
+    retrans_timer :: reference() | undefined,
+    next_retrans :: integer() | undefined
 }).
 
 
 -record(subscription, {
     id :: nksip_subscription_lib:id(),
     event :: nksip:token(),
-    expires :: pos_integer(),
+    expires :: pos_integer() | undefined,
     status :: nksip_subscription:status(),
     class :: uac | uas,
-    answered :: nklib_util:timestamp(),
-    timer_n :: reference(),
-    timer_expire :: reference(),
-    timer_middle :: reference(),
-    last_notify_cseq :: nksip:cseq()
+    answered :: nklib_util:timestamp() | undefined,
+    timer_n :: reference() | undefined,
+    timer_expire :: reference() | undefined,
+    timer_middle :: reference() | undefined,
+    last_notify_cseq :: nksip:cseq() | undefined
 }).
 
 
@@ -214,10 +214,10 @@
     call_id :: nksip:call_id(),
     created :: nklib_util:timestamp(),
     updated :: nklib_util:timestamp(),
-    local_seq :: 0 | nksip:cseq(),
-    remote_seq :: 0 | nksip:cseq(),
-    local_uri :: nksip:uri(),
-    remote_uri :: nksip:uri(),
+    local_seq :: 0 | nksip:cseq() | undefined,
+    remote_seq :: 0 | nksip:cseq() | undefined,
+    local_uri :: nksip:uri() | undefined,
+    remote_uri :: nksip:uri() | undefined,
     local_target :: nksip:uri(),        % Only for use in proxy
     remote_target :: nksip:uri(),
     route_set :: [nksip:uri()],
@@ -225,7 +225,7 @@
     early :: boolean(),
     secure :: boolean(),
     caller_tag :: nksip:tag(),
-    invite :: nksip:invite(),
+    invite :: nksip:invite() | undefined,
     subscriptions = [] :: [#subscription{}],
     supported = [] :: [nksip:token()],
     meta = [] :: nksip:optslist()
@@ -239,10 +239,10 @@
     nports = 1 :: integer(),
     proto = <<"RTP/AVP">> :: binary(),      
     fmt = [] :: [binary()],             % <<"0">>, <<"101">> ...
-    info :: binary(),
-    connect :: nksip_sdp:address(),
+    info :: binary() | undefined,
+    connect :: nksip_sdp:address() | undefined,
     bandwidth = [] :: [binary()],
-    key :: binary(),
+    key :: binary() | undefined,
     attributes = [] :: [nksip_sdp:sdp_a()]
 }).
 
@@ -253,15 +253,15 @@
     vsn = 0 :: non_neg_integer(), 
     address = {<<"IN">>, <<"IP4">>, <<"0.0.0.0">>} :: nksip_sdp:address(),
     session = <<"nksip">> :: binary(), 
-    info :: binary(),
-    uri :: binary(),
-    email :: binary(),
-    phone :: binary(),
-    connect :: nksip_sdp:address(),
+    info :: binary() | undefined,
+    uri :: binary() | undefined,
+    email :: binary() | undefined,
+    phone :: binary() | undefined,
+    connect :: nksip_sdp:address() | undefined,
     bandwidth = [] :: [binary()],
     time = [] :: [nksip_sdp:sdp_t()],
-    zone :: binary(),
-    key :: binary(),
+    zone :: binary() | undefined,
+    key :: binary() | undefined,
     attributes = [] :: [nksip_sdp:sdp_a()],
     medias = [] :: [nksip_sdp:sdp_m()]
 }).
diff --git a/include/nksip_call.hrl b/include/nksip_call.hrl
index 14744ba7..82518c01 100644
--- a/include/nksip_call.hrl
+++ b/include/nksip_call.hrl
@@ -71,27 +71,27 @@
 -record(trans, {
     id :: nksip_call:trans_id(),
     class :: uac | uas,
-    status :: nksip_call_uac:status() | nksip_call_uas:status(),
+    status :: nksip_call_uac:status() | nksip_call_uas:status() | undefined,
     start :: nklib_util:timestamp(),
-    from :: none | {srv, {pid(), term()}} | {fork, nksip_call_fork:id()},
+    from :: none | {srv, {pid(), term()}} | {fork, nksip_call_fork:id()} | undefined,
     opts :: nksip:optslist(),
-    trans_id :: integer(),
-    request :: nksip:request(),
+    trans_id :: integer() | undefined,
+    request :: nksip:request() | undefined,
     method :: nksip:method(),
     ruri :: nksip:uri(),
-    transp :: nkpacket:transport(),
-    response :: nksip:response(),
+    transp :: nkpacket:transport() | undefined,
+    response :: nksip:response() | undefined,
     code :: 0 | nksip:sip_code(),
     to_tags = [] :: [nksip:tag()],
-    stateless :: boolean(),
+    stateless :: boolean() | undefined,
     iter = 1 :: pos_integer(),
     cancel :: undefined | to_cancel | cancelled,
-    loop_id :: integer(),
-    timeout_timer :: {nksip_call_lib:timeout_timer(), reference()},
-    retrans_timer :: {nksip_call_lib:retrans_timer(), reference()},
-    next_retrans :: non_neg_integer(),
-    expire_timer :: {nksip_call_lib:expire_timer(), reference()},
-    ack_trans_id :: integer(),
+    loop_id :: integer() | undefined,
+    timeout_timer :: {nksip_call_lib:timeout_timer(), reference()} | undefined,
+    retrans_timer :: {nksip_call_lib:retrans_timer(), reference()} | undefined,
+    next_retrans :: non_neg_integer() | undefined,
+    expire_timer :: {nksip_call_lib:expire_timer(), reference()} | undefined,
+    ack_trans_id :: integer() | undefined,
     meta = [] :: nksip:optslist()
 }).
 
@@ -120,7 +120,7 @@
 
 -type call_auth() :: {
     nksip_dialog_lib:id(), 
-    nkpacket:nkport(), 
+    nkpacket:transport(), 
     inet:ip_address(), 
     inet:port_number()
 }.
@@ -173,8 +173,8 @@
     event_expires :: integer(),
     event_expires_offset :: integer(),
     nonce_timeout :: integer(),
-    from :: #uri{},
-    accept :: [binary()],
+    from :: #uri{} | undefined,
+    accept :: [binary()] | undefined,
     events :: [binary()],
     route :: [#uri{}],
     no_100 :: boolean(),
diff --git a/include/nksip_event_compositor.hrl b/include/nksip_event_compositor.hrl
index 63c12b90..d8d4ab11 100755
--- a/include/nksip_event_compositor.hrl
+++ b/include/nksip_event_compositor.hrl
@@ -21,7 +21,7 @@
 
 -record(reg_publish, {
     data :: nksip:body(),
-    expires :: nklib_util:timestamp(),
+    expires :: nklib_util:timestamp() | undefined,
     meta = [] :: nksip:optslist()  
 }).
 
diff --git a/include/nksip_registrar.hrl b/include/nksip_registrar.hrl
index 80d7970f..6b71002f 100755
--- a/include/nksip_registrar.hrl
+++ b/include/nksip_registrar.hrl
@@ -20,24 +20,24 @@
 
 
 -record(reg_contact, {
-    index :: nksip_registrar_lib:index(),
-    contact :: nksip:uri(), 
-    updated :: nklib_util:l_timestamp(),
-    expire :: nklib_util:timestamp(),
-    q :: float(),  
-    call_id :: nksip:call_id(),
-    cseq :: nksip:cseq(),
-    nkport :: nkpacket:nkport(),
-    path = [] :: [nksip:uri()],
-    meta = [] :: nksip:optslist()  
+    index :: nksip_registrar_lib:index() | undefined,
+    contact :: nksip:uri() | undefined,
+    updated :: nklib_util:l_timestamp() | undefined,
+    expire :: nklib_util:timestamp() | undefined,
+    q :: float() | undefined,
+    call_id :: nksip:call_id() | undefined,
+    cseq :: nksip:cseq() | undefined,
+    nkport :: nkpacket:nkport() | undefined,
+    path = [] :: [nksip:uri()] | undefined,
+    meta = [] :: nksip:optslist() | undefined
 }).
 
 -record(nksip_registrar_time, {
     min :: pos_integer(),
     max :: pos_integer(),
     default :: pos_integer(),
-    time :: pos_integer(),
-    time_long :: pos_integer()
+    time :: pos_integer() | undefined,
+    time_long :: pos_integer() | undefined
 }).
 
 
diff --git a/include/nksip_uac_auto_outbound.hrl b/include/nksip_uac_auto_outbound.hrl
index 6fab350a..cc9bdab1 100755
--- a/include/nksip_uac_auto_outbound.hrl
+++ b/include/nksip_uac_auto_outbound.hrl
@@ -23,8 +23,8 @@
     id :: term(),
     pos :: integer(),
     cseq :: nksip:cseq(),
-    conn_monitor :: reference(),
-    conn_pid :: pid(),
+    conn_monitor :: reference() | undefined,
+    conn_pid :: pid() | undefined,
     fails :: non_neg_integer()
 }).
 
diff --git a/include/nksip_uac_auto_register.hrl b/include/nksip_uac_auto_register.hrl
index b8a8e7e3..59200ecc 100755
--- a/include/nksip_uac_auto_register.hrl
+++ b/include/nksip_uac_auto_register.hrl
@@ -27,8 +27,8 @@
     interval :: non_neg_integer(),
     from :: any(),
     cseq :: nksip:cseq(),
-    next :: nklib_util:timestamp(),
-    ok :: boolean()
+    next :: nklib_util:timestamp() | undefined,
+    ok :: boolean() | undefined
 }).
 
 
diff --git a/rebar.config b/rebar.config
index 9a7906a0..1810f286 100644
--- a/rebar.config
+++ b/rebar.config
@@ -19,3 +19,5 @@
     {nkpacket, {git, "https://github.com/netcomposer/nkpacket", {branch, "master"}}},
     {nkserver, {git, "https://github.com/netcomposer/nkserver", {branch, "master"}}}
 ]}.
+
+{dialyzer, [{plt_extra_apps, [ nklib, nkpacket, nkserver, cowboy, cowlib, ranch ]}]}.
diff --git a/src/nksip.erl b/src/nksip.erl
index f087925e..f679ee8f 100644
--- a/src/nksip.erl
+++ b/src/nksip.erl
@@ -58,7 +58,7 @@
 
 -type config() ::
     #{
-        plugins => [atom()],
+        plugins => [any()],
         sip_listen => binary(),
         sip_allow => binary(),
         sip_supported => binary(),
@@ -224,7 +224,7 @@ stop(Id) ->
 
 %% @doc Retrieves a service as a supervisor child specification
 -spec get_sup_spec(id(), config()) ->
-    {ok, supervisor:child_spec()} | {error, term()}.
+    supervisor:child_spec().
 
 get_sup_spec(Id, Config) ->
     Config2 = nklib_util:to_map(Config),
diff --git a/src/nksip_auth.erl b/src/nksip_auth.erl
index 04d650f3..652bc87a 100644
--- a/src/nksip_auth.erl
+++ b/src/nksip_auth.erl
@@ -763,13 +763,13 @@ ha1_test() ->
     ?assertMatch(
         <<"194370e184088fb011b140d770936009">>,
         make_auth_response([], 'INVITE', <<"test@test.com">>, HA1, 
-                            <<"gfedcba">>, <<"abcdefg">>, 1)),
+                            <<"gfedcba">>, <<"abcdefg">>, <<"00000001">>)),
     ?assertMatch(
-        <<"788a70e3b5d371dc5f9dee5e59bb80cd">>,
+        <<"bf47fa2667ddc2be29b88d0cec6ae35e">>,
         make_auth_response([other, auth], 'INVITE', <<"test@test.com">>, HA1, 
-                            <<"gfedcba">>, <<"abcdefg">>, 1)),
+                            <<"gfedcba">>, <<"abcdefg">>, <<"00000001">>)),
     ?assertMatch(<<>>, make_auth_response([other], 'INVITE', <<"any">>, HA1, <<"any">>,
-                 <<"any">>, 1)),
+                 <<"any">>, <<"00000001">>)),
     [
         {scheme,digest},
         {realm,<<"av">>},
diff --git a/src/nksip_call_proxy.erl b/src/nksip_call_proxy.erl
index e813b634..db50dffa 100644
--- a/src/nksip_call_proxy.erl
+++ b/src/nksip_call_proxy.erl
@@ -38,7 +38,7 @@
 
 %% @doc Tries to route a request to set of uris, serially and/or in parallel.
 -spec route(nksip:uri_set(), nksip:optslist(), nksip_call:trans(), nksip_call:call()) -> 
-    {fork, nksip_call:trans(), nksip:uri_set()} | noreply | 
+    {fork, nksip_call:trans(), nksip:uri_set()} |
     {reply, nksip:sipreply(), nksip_call:call()}.
 
 route(UriList, ProxyOpts, UAS, Call) ->
@@ -197,7 +197,7 @@ check_request(#sipmsg{class={req, Method}, forwards=Forwards}=Req, Opts) ->
 
 %% @doc Process a UriSet generating a standard `[[nksip:uri()]]'.
 %% See test code for examples.
--spec normalize_uriset(nksip:uri_set()) ->
+-spec normalize_uriset(nksip:uri_set() | atom() | [atom()]) ->
     [[nksip:uri()]].
 
 normalize_uriset(#uri{}=Uri) ->
diff --git a/src/nksip_call_uac.erl b/src/nksip_call_uac.erl
index d35ac711..2ddfb6da 100644
--- a/src/nksip_call_uac.erl
+++ b/src/nksip_call_uac.erl
@@ -26,6 +26,7 @@
 -export([is_stateless/1, response/2]).
 -export_type([status/0, uac_from/0]).
 -import(nksip_call_lib, [update/2]).
+-dialyzer(no_missing_calls).
 
 -include("nksip.hrl").
 -include("nksip_call.hrl").
diff --git a/src/nksip_call_uac_make.erl b/src/nksip_call_uac_make.erl
index 77bbf410..9d3097c7 100644
--- a/src/nksip_call_uac_make.erl
+++ b/src/nksip_call_uac_make.erl
@@ -241,7 +241,7 @@ make_ack(#sipmsg{vias=[Via|_], cseq={CSeq, _}}=Req) ->
 
 
 %% @private
--spec parse_opts(nksip:optslist(), nksip:request(), nksip:optslist()) ->
+-spec parse_opts([nksip_uac:req_option()], nksip:request(), nksip:optslist()) ->
     {nksip:request(), nksip:optslist()}.
 
 
@@ -494,7 +494,7 @@ parse_opts([Term|Rest], Req, Opts) ->
 
 %% @private
 -spec parse_plugin_opts(nksip:request(), map()) ->
-    {nksip:request(), map()}.
+    {nksip:request(), [nksip_uac:req_option()]}.
 
 parse_plugin_opts(#sipmsg{srv_id=SrvId}=Req, Opts) ->
     case ?CALL_SRV(SrvId, nksip_parse_uac_opts, [Req, Opts]) of
diff --git a/src/nksip_call_uac_transp.erl b/src/nksip_call_uac_transp.erl
index 1ce8dc9d..4f81dd15 100644
--- a/src/nksip_call_uac_transp.erl
+++ b/src/nksip_call_uac_transp.erl
@@ -23,6 +23,7 @@
 -author('Carlos Gonzalez <carlosj.gf@gmail.com>').
 
 -export([send_request/3, resend_request/2, add_headers/6]).
+-dialyzer(no_missing_calls).
 
 -include_lib("nklib/include/nklib.hrl").
 -include_lib("nkpacket/include/nkpacket.hrl").
@@ -128,7 +129,7 @@ send_request(Req, Call, Opts) ->
 -spec resend_request(nksip:request(), nksip:optslist()) ->
     {ok, nksip:request()} | error.
 
-resend_request(#sipmsg{ srv_id=SrvId, nkport=NkPort}=Req, Opts) ->
+resend_request(#sipmsg{ srv_id=SrvId, nkport=NkPort}=Req, Opts) when NkPort =/= undefined ->
     Msg = fun(NkPort2) -> Req#sipmsg{nkport=NkPort2} end,
     nksip_util:send(SrvId, [NkPort], Msg, Opts).
         
diff --git a/src/nksip_call_uas.erl b/src/nksip_call_uas.erl
index b46d3884..bbd71b1b 100644
--- a/src/nksip_call_uas.erl
+++ b/src/nksip_call_uas.erl
@@ -24,6 +24,7 @@
 
 -export([request/2, reply/3, do_reply/3]).
 -export_type([status/0, incoming/0]).
+-dialyzer(no_missing_calls).
 
 -import(nksip_call_lib, [update/2]).
 -include_lib("nklib/include/nklib.hrl").
diff --git a/src/nksip_call_uas_route.erl b/src/nksip_call_uas_route.erl
index 62feb0d5..b8b2f0fe 100644
--- a/src/nksip_call_uas_route.erl
+++ b/src/nksip_call_uas_route.erl
@@ -278,9 +278,6 @@ do_route(process_stateless, UAS, Call) ->
 do_route({proxy, UriList, ProxyOpts}, UAS, Call) ->
     #trans{id=Id, opts=Opts, method=Method} = UAS,
     case nksip_call_proxy:route(UriList, ProxyOpts, UAS, Call) of
-        noreply ->
-            UAS1 = UAS#trans{status=finished},
-            update(UAS1, Call);
         {fork, _, _, _} when Method=='CANCEL' ->
             nksip_call_uas:do_reply(no_transaction, UAS, Call);
         {fork, UAS1, UriSet, ProxyOpts1} ->
diff --git a/src/nksip_call_uas_transp.erl b/src/nksip_call_uas_transp.erl
index c51e610f..4b5abcb2 100644
--- a/src/nksip_call_uas_transp.erl
+++ b/src/nksip_call_uas_transp.erl
@@ -23,6 +23,7 @@
 -author('Carlos Gonzalez <carlosj.gf@gmail.com>').
 
 -export([send_response/2, resend_response/2]).
+-dialyzer(no_missing_calls).
     
 -include_lib("nklib/include/nklib.hrl").
 -include_lib("nkpacket/include/nkpacket.hrl").
diff --git a/src/nksip_call_worker.erl b/src/nksip_call_worker.erl
index e0d6d4c5..cc544a14 100644
--- a/src/nksip_call_worker.erl
+++ b/src/nksip_call_worker.erl
@@ -44,6 +44,7 @@
     {cancel, nksip_sipmsg:id()} |
     {send_reply, nksip_sipmsg:id(), nksip:sipreply()} |
     {incoming, #sipmsg{}} | 
+    {incoming, #nkport{}, binary()} | 
     {incoming, nkserver:id(), nkservice:id(), nksip:call_id(), nkpacket:nkport(), binary()} |
     info |
     get_all_dialogs | 
diff --git a/src/nksip_dialog.erl b/src/nksip_dialog.erl
index 4713c6eb..21dd6d34 100644
--- a/src/nksip_dialog.erl
+++ b/src/nksip_dialog.erl
@@ -108,7 +108,7 @@ call_id(Handle) ->
 
 
 %% @doc Get a specific metadata
--spec get_meta(field(), nksip:dialog()|nksip:handle()) ->
+-spec get_meta(field() | {function, function()}, nksip:dialog()|nksip:handle()) ->
     {ok, term()} | {error, term()}.
 
 get_meta(Field, #dialog{}=Dialog) ->
diff --git a/src/nksip_dialog_lib.erl b/src/nksip_dialog_lib.erl
index 61bd8927..68e2345f 100644
--- a/src/nksip_dialog_lib.erl
+++ b/src/nksip_dialog_lib.erl
@@ -86,7 +86,7 @@ parse_handle(_O) ->
 
 
 %% @doc Get specific metadata from the dialog
--spec get_meta(nksip_dialog:field(), nksip:dialog()) ->
+-spec get_meta(nksip_dialog:field() | {function, function()}, nksip:dialog()) -> 
     term().
 
 get_meta(Field, #dialog{invite=I}=D) ->
@@ -166,7 +166,7 @@ get_meta(Field, #dialog{invite=I}=D) ->
     end.
 
 %% @doc Get specific metadata from the dialog
--spec get_metas([nksip_dialog:field()], nksip:dialog()|nksip:handle()) ->
+-spec get_metas([nksip_dialog:field() | {function, function()}], nksip:dialog()|nksip:handle()) -> 
     [{nksip_dialog:field(), term()}].
 
 get_metas(Fields, #dialog{}=Dialog) when is_list(Fields) ->
@@ -187,7 +187,7 @@ remote_meta(Field, Handle) ->
 
 
 %% @doc Extracts remote metas
--spec remote_metas([nksip_dialog:field()], nksip:handle()) ->
+-spec remote_metas([nksip_dialog:field() | {function, function()}], nksip:handle()) ->
     {ok, [{nksip_dialog:field(), term()}]} | {error, term()}.
 
 remote_metas(Fields, Handle) when is_list(Fields) ->
diff --git a/src/nksip_parse.erl b/src/nksip_parse.erl
index 06c299af..7e47cbf4 100644
--- a/src/nksip_parse.erl
+++ b/src/nksip_parse.erl
@@ -161,7 +161,7 @@ vias(Term) ->
         UriOrVia    :: nksip:uri()
             | other_test 
             | nksip:via(),
-        Transport   :: nkpacket:transport(), 
+        Transport   :: nkpacket:transport() | binary(), 
         Host        :: binary(),
         Port        :: inet:port_number().
 
diff --git a/src/nksip_parse_header.erl b/src/nksip_parse_header.erl
index 7acac055..4919b0af 100644
--- a/src/nksip_parse_header.erl
+++ b/src/nksip_parse_header.erl
@@ -486,10 +486,14 @@ uri_test() ->
     [#uri{headers=UriHeaders}] = nklib_parse:uris(Uri),
 
     Base = #sipmsg{
+        id = <<"id">>,
+        class = {req, 'MESSAGE'},
+        call_id = <<"call-id">>,
         from = {#uri{domain = <<"f">>, ext_opts=[{<<"tag">>, <<"f">>}]}, <<"f">>},
         to = {#uri{domain = <<"t">>, ext_opts=[{<<"tag">>, <<"t">>}]}, <<"t">>},
         headers = [{<<"previous">>, <<"term">>}],
-        routes = [#uri{domain = <<"previous">>}]
+        routes = [#uri{domain = <<"previous">>}],
+        start = nklib_util:timestamp()
     },
 
     Req1 = headers(UriHeaders, Base, add),
diff --git a/src/nksip_protocol.erl b/src/nksip_protocol.erl
index 70710c88..086f1ed4 100644
--- a/src/nksip_protocol.erl
+++ b/src/nksip_protocol.erl
@@ -35,6 +35,9 @@
 -include_lib("nkpacket/include/nkpacket.hrl").
 -include_lib("nkserver/include/nkserver.hrl").
 
+-dialyzer(no_missing_calls).
+-dialyzer(no_undefined_callbacks).
+
 
 -define(MAX_MSG, 65507).
 
@@ -123,10 +126,10 @@ naptr(_, _) -> invalid.
     buffer = <<>> :: binary(),
     rnrn_pattern :: binary:cp(),
     in_refresh = false :: boolean(),
-    refresh_time :: pos_integer(),
-    refresh_timer :: reference(),
-    nat_ip :: inet:ip_address(),
-    nat_port :: inet:port_number(),
+    refresh_time :: pos_integer() | undefined,
+    refresh_timer :: reference() | undefined,
+    nat_ip :: inet:ip_address() | undefined,
+    nat_port :: inet:port_number() | undefined,
     refresh_notify = [] :: [{pid(), term()}]
 }).
 
@@ -154,7 +157,7 @@ conn_init(NkPort) ->
 
 %% @doc This function is called when a new message arrives to the connection
 -spec conn_parse(nkpacket:incoming()|close, nkpacket:nkport(), conn_state()) ->
-    {ok, conn_state()} | {bridge, nkpacket:nkport()} | 
+    {ok, conn_state()} | {bridge, nkpacket:nkport(), conn_state()} | 
     {stop, Reason::term(), conn_state()}.
 
 conn_parse(close, _NkPort, State) ->
@@ -183,15 +186,14 @@ conn_parse(Binary, NkPort, #conn_state{buffer=Buffer}=State) ->
 
 %% @doc This function is called when a new message must be send to the connection
 -spec conn_encode(term(), nkpacket:nkport(), conn_state()) ->
-    {ok, nkpacket:outcoming(), conn_state()} | {error, term(), conn_state()} |
-    {stop, Reason::term(), conn_state()}.
+    {error, term(), conn_state()}.
 
 conn_encode(_Term, _NkPort, ConnState) ->
     {error, not_defined, ConnState}.
 
 
 -spec conn_encode(nksip:request()|nksip:response(), nkpacket:nkport()) ->
-    {ok, nkpacket:outcoming()} | continue | {error, term()}.
+    {ok, nkpacket:outcoming()}.
 
 conn_encode(#sipmsg{srv_id=SrvId}=SipMsg, _NkPort) ->
     Packet = nksip_unparse:packet(SipMsg),
diff --git a/src/nksip_router.erl b/src/nksip_router.erl
index 565d7531..03ce236f 100644
--- a/src/nksip_router.erl
+++ b/src/nksip_router.erl
@@ -30,6 +30,8 @@
 -export([init/1, terminate/2, code_change/3, handle_call/3, handle_cast/2,
             handle_info/2]).
 
+-dialyzer(no_missing_calls).
+
 -include("nksip.hrl").
 -include("nksip_call.hrl").
 
@@ -50,7 +52,7 @@ send_work(SrvId, CallId, Work) ->
 
 %% @doc Called when a new request or response has been received.
 -spec incoming(nkserver:id(), nksip:call_id(), nkpacket:nkport(), binary()) ->
-    ok | {error, too_many_calls | looped_process | {exit, term()}}.
+    any() | {error, too_many_calls | looped_process | {exit, term()}}.
 
 incoming(SrvId, CallId, NkPort, Msg) ->
     Work = {incoming, NkPort, Msg},
@@ -58,7 +60,7 @@ incoming(SrvId, CallId, NkPort, Msg) ->
 
 
 %% @doc Sends a synchronous piece of {@link nksip_call_worker:work()} to a call.
--spec send_work(nkserver:id(), nksip:call_id(), nksip_call_worker:work(), pid()) ->
+-spec send_work(nkserver:id(), nksip:call_id(), nksip_call_worker:work(), pid() | none) ->
     any() | {error, too_many_calls | looped_process | {exit, term()}}.
 
 send_work(SrvId, CallId, Work, Caller) ->
@@ -232,8 +234,8 @@ worker_name(CallId) ->
 
 
 %% @private
--spec send_work_sync(nkserver:id(), nksip:call_id(), nksip_call_worker:work(),
-                     pid() | none, {pid(), term()}, #state{}) ->
+-spec send_work_sync(nksip:srv_id(), nksip:call_id(), nksip_call_worker:work(), 
+                     pid() | none, {pid(), term()} | none, #state{}) ->
     {ok, #state{}} | {error, looped_process | service_not_found | too_many_calls}.
 
 send_work_sync(SrvId, CallId, Work, Caller, From, State) ->
diff --git a/src/nksip_sample.erl b/src/nksip_sample.erl
deleted file mode 100755
index 054ae9a4..00000000
--- a/src/nksip_sample.erl
+++ /dev/null
@@ -1,50 +0,0 @@
-%% -------------------------------------------------------------------
-%%
-%% Copyright (c) 2019 Carlos Gonzalez Florido.  All Rights Reserved.
-%%
-%% This file is provided to you under the Apache License,
-%% Version 2.0 (the "License"); you may not use this file
-%% except in compliance with the License.  You may obtain
-%% a copy of the License at
-%%
-%%   http://www.apache.org/licenses/LICENSE-2.0
-%%
-%% Unless required by applicable law or agreed to in writing,
-%% software distributed under the License is distributed on an
-%% "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
-%% KIND, either express or implied.  See the License for the
-%% specific language governing permissions and limitations
-%% under the License.
-%%
-%% -------------------------------------------------------------------
-
-%% @doc Companion code for NkSIP Tutorial.
-
-
--module(nksip_sample).
--author('Carlos Gonzalez <carlosj.gf@gmail.com>').
-
--export([start/0, stop/0]).
--export([s1/0]).
-
--define(NAME, test).
-
-
-
-%% @doc Launches the full tutorial.
-start() ->
-    Spec = #{
-        callback => ?MODULE,
-        sip_debug => [nkpacket, call, protocol]
-
-    },
-    nksip:start(?NAME, Spec).
-
-
-
-stop() ->
-    nksip:stop(?NAME).
-
-
-s1() ->
-    nksip_uac:options(?NAME, <<"sip1">>, "<sip:carlosj.sip.us1.twilio.com>;transport=tcp", []).
\ No newline at end of file
diff --git a/src/nksip_sdp.erl b/src/nksip_sdp.erl
index 0a4a077a..8286357d 100644
--- a/src/nksip_sdp.erl
+++ b/src/nksip_sdp.erl
@@ -27,6 +27,8 @@
 -export([new/2, new/0, empty/0, update/2, increment/1, parse/1, unparse/1]).
 -export([is_sdp/1, is_new/2, update_ip/2]).
 
+-dialyzer(no_behaviours).
+
 -export_type([sdp/0, sdp_a/0, sdp_m/0, sdp_t/0, address/0]).
 
 %% ===================================================================
@@ -54,7 +56,7 @@
                         Media :: binary(),              % <<"audio">>, <<"video">>
                         Port :: inet:port_number(), 
                         Attributes :: 
-                            [{rtpmap, Pos::integer(), Data::binary()} | binary()]
+                            [{rtpmap, Pos::integer(), Data::string() | binary()} | binary()]
                     }.
 
 
@@ -669,8 +671,8 @@ sdp2_test() ->
 
 sdp3_test() ->
     Media = [
-        {<<"audio">>, 10000, [{rtpmap, 0, "Params0"}, {rtpmap, 1, "Params1"}, sendrecv]},
-        {<<"video">>, 10001, [{rtpmap, 2, "Params2"}, {rtpmap, 3, "Params3"}, sendrecv]}
+        {<<"audio">>, 10000, [{rtpmap, 0, "Params0"}, {rtpmap, 1, "Params1"}, <<"sendrecv">>]},
+        {<<"video">>, 10001, [{rtpmap, 2, "Params2"}, {rtpmap, 3, "Params3"}, <<"sendrecv">>]}
     ],
     #sdp{id=Id, vsn=Vsn} = SDP = new("local", Media),
     Bin = list_to_binary([
diff --git a/src/nksip_sdp_util.erl b/src/nksip_sdp_util.erl
index 96b79e60..bc877d3a 100755
--- a/src/nksip_sdp_util.erl
+++ b/src/nksip_sdp_util.erl
@@ -61,12 +61,8 @@
     #sdp{} | {error, term()}.
 
 add_candidates(#sdp{medias=Medias}=SDP, Candidates) ->
-    case add_candidates(Medias, 0, Candidates, []) of
-        {ok, Medias2} ->
-            SDP#sdp{medias=Medias2};
-        {error, Error} ->
-            {error, Error}
-    end;
+    {ok, Medias2} = add_candidates(Medias, 0, Candidates, []),
+    SDP#sdp{medias=Medias2};
 
 add_candidates(SDP, Candidates) ->
     case nksip_sdp:parse(SDP) of
diff --git a/src/nksip_sup.erl b/src/nksip_sup.erl
index 0feacfb4..6a5fe19f 100644
--- a/src/nksip_sup.erl
+++ b/src/nksip_sup.erl
@@ -26,6 +26,7 @@
 
 % -export([start_sipapp/2, stop_sipapp/1]).
 -export([init/1, start_link/0]).
+-dialyzer(no_missing_calls).
 
 -include("nksip.hrl").
 
diff --git a/src/nksip_uac.erl b/src/nksip_uac.erl
index b5a14a1d..8405c24f 100644
--- a/src/nksip_uac.erl
+++ b/src/nksip_uac.erl
@@ -66,8 +66,14 @@
     allow |
     accept |
     allow_event |
+    contact |
 
     % Special parameters
+    async |
+    ignore |
+    auto_2xx_ack |
+
+    date |
     to_as_from |
     {body, value()} |
     {cseq_num, value()} |
@@ -89,6 +95,7 @@
     % Subscription
     {subscription_state, term()} |
     {refer_to, binary()} |
+    {refer_subscription_id, binary()} |
 
     % Publish
     {sip_if_match, binary()} |
diff --git a/src/nksip_util.erl b/src/nksip_util.erl
index 9e44a30e..452cf106 100644
--- a/src/nksip_util.erl
+++ b/src/nksip_util.erl
@@ -27,6 +27,8 @@
 -export([get_connected/2, get_connected/5, is_local/2, send/4]).
 -export([print_all/0, user_callback/3]).
 
+-dialyzer(no_missing_calls).
+
 -include_lib("nklib/include/nklib.hrl").
 -include_lib("nkpacket/include/nkpacket.hrl").
 -include_lib("nkserver/include/nkserver.hrl").
@@ -166,8 +168,8 @@ is_local(SrvId, #via{}=Via) ->
 
 %% @private
 -spec send(nkserver:id(), [nkpacket:send_spec()],
-           nksip:request()|nksip:response()|function(),
-           [nksip_uac:req_option()]) ->
+           function()|nksip:request()|nksip:response(),
+           list()) ->
     {ok, #sipmsg{}} | {error, term()}.
 
 send(SrvId, Spec, Msg, Opts) when is_list(Spec) ->
diff --git a/src/plugins/nksip_debug.erl b/src/plugins/nksip_debug.erl
index c3f67a92..e741e675 100755
--- a/src/plugins/nksip_debug.erl
+++ b/src/plugins/nksip_debug.erl
@@ -43,7 +43,7 @@
 start(SrvId) ->
     Plugins1 = ?CALL_SRV(SrvId, plugins, []),
     Plugins2 = nklib_util:store_value(nksip_debug, Plugins1),
-    case nksip:update(SrvId, #{plugins=>Plugins2, sip_debug=>true}) of
+    case nksip:update(SrvId, #{plugins=>Plugins2, sip_debug=>[nkpacket,call,protocol]}) of
         ok ->
             ok;
         {error, Error} ->
@@ -58,7 +58,7 @@ start(SrvId) ->
 stop(SrvId) ->
     Plugins1 = ?CALL_SRV(SrvId, plugins, []),
     Plugins2 = Plugins1 -- [nksip_debug],
-    case nksip:update(SrvId, #{plugins=>Plugins2, sip_debug=>false}) of
+    case nksip:update(SrvId, #{plugins=>Plugins2, sip_debug=>[]}) of
         ok ->
             ok;
         {error, Error} ->
diff --git a/src/plugins/nksip_gruu_lib.erl b/src/plugins/nksip_gruu_lib.erl
index 9cb84eb4..8b2a93a4 100755
--- a/src/plugins/nksip_gruu_lib.erl
+++ b/src/plugins/nksip_gruu_lib.erl
@@ -28,6 +28,7 @@
 -include("nksip_registrar.hrl").
 
 -export([find/2, update_gruu/1, check_gr/2, update_regcontact/4]).
+-dialyzer(no_missing_calls).
 
 -define(AES_IV, <<"12345678abcdefgh">>).
 
diff --git a/src/plugins/nksip_outbound.erl b/src/plugins/nksip_outbound.erl
index 8a4d08c7..b23ab0c8 100755
--- a/src/plugins/nksip_outbound.erl
+++ b/src/plugins/nksip_outbound.erl
@@ -25,6 +25,7 @@
 -export([proxy_opts/2, add_headers/6, check_several_reg_id/1]).
 -export([registrar/1]).
 -export([decode_flow/1]).
+-dialyzer(no_missing_calls).
 
 -include_lib("nklib/include/nklib.hrl").
 -include_lib("nkpacket/include/nkpacket.hrl").
@@ -176,7 +177,7 @@ do_proxy_opts(Req, Opts, [Route|RestRoutes]) ->
             case lists:member(<<"ob">>, RouteOpts) of
                 true ->
                     Opts1 = case nksip_util:get_connected(SrvId, NkPort) of
-                        [{_, Pid}|_] ->
+                        [Pid|_] when is_pid(Pid) ->
                             [{record_flow, Pid}|Opts];
                         _ ->
                             Opts
@@ -244,7 +245,7 @@ add_headers(Req, Opts, Scheme, Transp, ListenHost, ListenPort) ->
             end,
             RouteHash = nklib_util:hash({GlobalId, SrvId, RouteBranch}),
             <<"NkQ", RouteHash/binary>>;
-        FlowPid ->
+        _ ->
             FlowToken = encode_flow(FlowPid),
             <<"NkF", FlowToken/binary>>
     end,
@@ -367,7 +368,7 @@ check_several_reg_id([#uri{ext_opts=Opts}|Rest], Found) ->
 
 %% @private
 -spec registrar(nksip:request()) ->
-    {boolean(), nksip:request()} | no_outbound.
+    {boolean(), nksip:request()} | {error, nksip:sipreply()} | no_outbound.
 
 registrar(Req) ->
     #sipmsg{ srv_id=SrvId, vias=Vias, nkport=NkPort} = Req,
diff --git a/src/plugins/nksip_stats_srv.erl b/src/plugins/nksip_stats_srv.erl
index 7891def3..874f8555 100755
--- a/src/plugins/nksip_stats_srv.erl
+++ b/src/plugins/nksip_stats_srv.erl
@@ -61,8 +61,8 @@ init([Period]) ->
 
 
 %% @private
--spec handle_call(term(), {pid(), term()}, #state{}) ->
-    {reply, term(), #state{}} | {noreply, #state{}}.
+-spec handle_call(term(), {pid(), term()} | term(), #state{}) ->
+    {reply, term(), #state{}, non_neg_integer()} | {noreply, #state{}, non_neg_integer()}.
 
 
 handle_call(get_uas_avg, _From, #state{last_uas=LastUas}=State) ->
@@ -75,7 +75,7 @@ handle_call(Msg, _From, State) ->
 
 %% @private
 -spec handle_cast(term(), #state{}) ->
-    {noreply, #state{}}.
+    {noreply, #state{}, non_neg_integer()}.
 
 handle_cast({response_time, Time}, #state{avg_uas_values=Values}=State) ->
     State1 = State#state{avg_uas_values=[Time|Values]},
@@ -88,7 +88,7 @@ handle_cast(Msg, State) ->
 
 %% @private
 -spec handle_info(term(), #state{}) ->
-    {noreply, #state{}}.
+    {noreply, #state{}, non_neg_integer()}.
 
 handle_info(timeout, #state{avg_uas_values=Values, period=Period}=State) ->
     LastUas = calculate(Values),
@@ -124,6 +124,8 @@ terminate(_Reason, _State) ->
 
 
 %% @private
+-spec timeout(#state{}) -> non_neg_integer().
+
 timeout(#state{last_check=Last, period=Period}) ->
     case (Last+Period) - nklib_util:timestamp() of
         Time when Time > 0 ->
diff --git a/src/plugins/nksip_timers_callbacks.erl b/src/plugins/nksip_timers_callbacks.erl
index e571bd8e..9562bb1f 100755
--- a/src/plugins/nksip_timers_callbacks.erl
+++ b/src/plugins/nksip_timers_callbacks.erl
@@ -200,7 +200,8 @@ nksip_uac_response(Req, Resp, UAC, Call) ->
 %% @doc Called when preparing a UAS dialog response
 -spec nksip_uas_dialog_response(nksip:request(), nksip:response(),
                                nksip:optslist(), nksip:call()) ->
-    {ok, nksip:response(), nksip:optslist()} | continue.
+    {ok, nksip:response(), nksip:optslist()} |
+    {continue, [nksip:request() | nksip:response() | nksip:optslist() | nksip:call()]}.
 
 nksip_uas_dialog_response(Req, Resp, Opts, Call) ->
     Resp1 = case Req of
diff --git a/src/plugins/nksip_trace.erl b/src/plugins/nksip_trace.erl
old mode 100755
new mode 100644
diff --git a/src/plugins/nksip_uac_auto_outbound_callbacks.erl b/src/plugins/nksip_uac_auto_outbound_callbacks.erl
index 7a668b01..51016aa0 100755
--- a/src/plugins/nksip_uac_auto_outbound_callbacks.erl
+++ b/src/plugins/nksip_uac_auto_outbound_callbacks.erl
@@ -125,8 +125,8 @@ srv_handle_info(_Msg, _Service, _State) ->
 
 
 %% @doc Called when the plugin is shutdown
--spec srv_terminate(nkserver:id(), nkserver:service(), map()) ->
-    {ok, map()}.
+-spec srv_terminate(atom(), term(), map()) ->
+    {continue, [term()]}.
 
 srv_terminate(Reason, Service, State) ->
     State2 = case State of
diff --git a/src/plugins/nksip_uac_auto_register_callbacks.erl b/src/plugins/nksip_uac_auto_register_callbacks.erl
index 25c44702..77e71fd3 100755
--- a/src/plugins/nksip_uac_auto_register_callbacks.erl
+++ b/src/plugins/nksip_uac_auto_register_callbacks.erl
@@ -226,7 +226,7 @@ srv_handle_cast(nksip_uac_auto_register_check,
     {noreply, State2#{nksip_uac_auto_register:=RegState2#state{pings=Pings1, regs=Regs2}}};
 
 srv_handle_cast(nksip_uac_auto_register_terminate, Service, SrvState) ->
-    {ok, SrvState1} = srv_terminate(normal, Service, SrvState),
+    {continue, [_, _, SrvState1]} = srv_terminate(normal, Service, SrvState),
     {noreply, SrvState1};
 
 srv_handle_cast(_Msg, _Service, _State) ->
diff --git a/test/tests/t22_ipv6.erl b/test/tests/t22_ipv6.erl
old mode 100755
new mode 100644
index 9df2e306..ca02f809
--- a/test/tests/t22_ipv6.erl
+++ b/test/tests/t22_ipv6.erl
@@ -28,6 +28,8 @@
 -include_lib("nklib/include/nklib.hrl").
 
 -compile([export_all, nowarn_export_all]).
+-dialyzer(no_missing_calls).
+
 -define(RECV(T), receive T -> ok after 1000 -> error(recv) end).
 
 ipv6_gen() ->