Hi, thanks for this implementation webrtc of flutter

When I try to register to my webrtc error I get following error.

Log output:

I/flutter (21450): �[38;5;208m[2019-11-18 16:03:16.324] Level.warning sip_ua_helper.dart:127 ::: UA instance already exist!, stopping UA and creating a new one...�[0m
I/flutter (21450): [2019-11-18 16:03:16.330] Level.debug ua.dart:282 ::: stop()
I/flutter (21450): [2019-11-18 16:03:16.337] Level.debug transport.dart:138 ::: close()
I/flutter (21450): [2019-11-18 16:03:16.343] Level.debug websocket_interface.dart:147 ::: disconnect()
I/flutter (21450): [2019-11-18 16:03:16.348] Level.debug websocket_interface.dart:204 ::: WebSocket wss://kam13.x2one.com:8443 closed
I/flutter (21450): [2019-11-18 16:03:16.354] Level.debug sip_ua_helper.dart:158 ::: disconnected => Code: [0], Cause: disconnect, Reason: close by local
I/flutter (21450): [2019-11-18 16:03:16.362] Level.debug websocket_interface.dart:32 ::: new() [url:wss://kam13.x2one.com:8443]
I/flutter (21450): [2019-11-18 16:03:16.372] Level.debug websocket_interface.dart:44 ::: SIP URI: sip:kam13.x2one.com:8443;transport=ws
I/flutter (21450): [2019-11-18 16:03:16.378] Level.debug ua.dart:103 ::: new() [configuration:Instance of 'Settings']
I/flutter (21450): �[38;5;12m[2019-11-18 16:03:16.384] Level.info config.dart:246 ::: Check mandatory parameter => sockets.�[0m
I/flutter (21450): �[38;5;12m[2019-11-18 16:03:16.409] Level.info config.dart:246 ::: Check mandatory parameter => uri.�[0m
I/flutter (21450): [2019-11-18 16:03:16.418] Level.debug config.dart:252 ::: Check optional parameter => authorization_user.
I/flutter (21450): [2019-11-18 16:03:16.427] Level.debug config.dart:252 ::: Check optional parameter => user_agent.
I/flutter (21450): [2019-11-18 16:03:16.431] Level.debug config.dart:252 ::: Check optional parameter => connection_recovery_max_interval.
I/flutter (21450): [2019-11-18 16:03:16.436] Level.debug config.dart:252 ::: Check optional parameter => connection_recovery_min_interval.
I/flutter (21450): [2019-11-18 16:03:16.441] Level.debug config.dart:252 ::: Check optional parameter => contact_uri.
I/flutter (21450): [2019-11-18 16:03:16.446] Level.debug config.dart:252 ::: Check optional parameter => display_name.
I/flutter (21450): [2019-11-18 16:03:16.451] Level.debug config.dart:252 ::: Check optional parameter => instance_id.
I/flutter (21450): [2019-11-18 16:03:16.455] Level.debug config.dart:252 ::: Check optional parameter => no_answer_timeout.
I/flutter (21450): [2019-11-18 16:03:16.460] Level.debug config.dart:252 ::: Check optional parameter => session_timers.
I/flutter (21450): [2019-11-18 16:03:16.465] Level.debug config.dart:252 ::: Check optional parameter => session_timers_refresh_method.
I/flutter (21450): [2019-11-18 16:03:16.469] Level.debug config.dart:252 ::: Check optional parameter => password.
I/flutter (21450): [2019-11-18 16:03:16.475] Level.debug config.dart:252 ::: Check optional parameter => realm.
I/flutter (21450): [2019-11-18 16:03:16.479] Level.debug config.dart:252 ::: Check optional parameter => ha1.
I/flutter (21450): [2019-11-18 16:03:16.484] Level.debug config.dart:252 ::: Check optional parameter => register.
I/flutter (21450): [2019-11-18 16:03:16.490] Level.debug config.dart:252 ::: Check optional parameter => register_expires.
I/flutter (21450): [2019-11-18 16:03:16.496] Level.debug config.dart:252 ::: Check optional parameter => registrar_server.
I/flutter (21450): [2019-11-18 16:03:16.501] Level.debug config.dart:252 ::: Check optional parameter => use_preloaded_route.
I/flutter (21450): [2019-11-18 16:03:16.507] Level.debug transport.dart:53 ::: new()
I/flutter (21450): [2019-11-18 16:03:16.516] Level.debug ua.dart:163 ::: start()
I/flutter (21450): [2019-11-18 16:03:16.520] Level.debug transport.dart:111 ::: connect()
I/flutter (21450): [2019-11-18 16:03:16.524] Level.debug ua.dart:844 ::: Transport connecting
I/flutter (21450): [2019-11-18 16:03:16.529] Level.debug sip_ua_helper.dart:146 ::: connecting => Instance of 'EventSocketConnecting'
I/flutter (21450): [2019-11-18 16:03:16.534] Level.debug websocket_interface.dart:104 ::: connect()
I/flutter (21450): [2019-11-18 16:03:16.549] Level.debug websocket_interface.dart:115 ::: connecting to WebSocket wss://kam13.x2one.com:8443
I/flutter (21450): �[38;5;196m[2019-11-18 16:03:16.620] Level.error websocket_interface.dart:139 ::: HandshakeException: Handshake error in client (OS Error:
I/flutter (21450): CERTIFICATE_VERIFY_FAILED: unable to get local issuer certificate(handshake.cc:352))�[0m
I/flutter (21450): �[38;5;196m#0 WebSocketInterface.connect (package:sip_ua/src/websocket_interface.dart:117:18)
I/flutter (21450):
I/flutter (21450): #1 Transport.connect (package:sip_ua/src/transport.dart:132:19)
I/flutter (21450): #2 UA.start (package:sip_ua/src/ua.dart:166:23)
I/flutter (21450): #3 SIPUAHelper.start (package:sip_ua/src/sip_ua_helper.dart:197:16)
I/flutter (21450):
I/flutter (21450): #4 _MyRegisterWidget._handleSave (package:dart_sip_ua_example/src/register.dart:137:12)
I/flutter (21450): #5 _MyRegisterWidget.build. (package:dart_sip_ua_example/src/register.dart:320:44)
I/flutter (21450): #6 _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:654:14)
I/flutter (21450): #7 _InkResponseState.build. (package:flutter/src/material/ink_well.dart:729:32)
I/flutter (21450): #8 GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:182:24)
I/flutter (21450): #9 TapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:365:11)
I/flutter (21450): #10 TapGestureRecognizer.handlePrimaryPointer (package:flutter/src/gestures/tap.dart:275:7)
I/flutter (21450): #11
I/flutter (21450): �[38;5;196m[2019-11-18 16:03:16.628] Level.error websocket_interface.dart:223 ::: WebSocket wss://kam13.x2one.com:8443 error: HandshakeException: Handshake error in client (OS Error:
I/flutter (21450): CERTIFICATE_VERIFY_FAILED: unable to get local issuer certificate(handshake.cc:352))�[0m

Thanks,
Oleg