I was able to deal with this problem, I used to order a public list of servers STUN and TURN found here https://gist.github.com/yetithefoot/7592580. It was enough that I added in the file c2mp.js to "var DEFAULT_ICE_SERVER_LIST" other servers STUN and TURN, at the moment it looks like this:
var DEFAULT_ICE_SERVER_LIST = [
{url:'stun:stun01.sipphone.com'},
{url:'stun:stun.ekiga.net'},
{url:'stun:stun.fwdnet.net'},
{url:'stun:stun.ideasip.com'},
{url:'stun:stun.iptel.org'},
{url:'stun:stun.rixtelecom.se'},
{url:'stun:stun.schlund.de'},
{url:'stun:stun.l.google.com:19302'},
{url:'stun:stun1.l.google.com:19302'},
{url:'stun:stun2.l.google.com:19302'},
{url:'stun:stun3.l.google.com:19302'},
{url:'stun:stun4.l.google.com:19302'},
{url:'stun:stunserver.org'},
{url:'stun:stun.softjoys.com'},
{url:'stun:stun.voiparound.com'},
{url:'stun:stun.voipbuster.com'},
{url:'stun:stun.voipstunt.com'},
{url:'stun:stun.voxgratia.org'},
{url:'stun:stun.xten.com'},
{
url: 'turn:numb.viagenie.ca',
credential: 'muazkh',
username: 'webrtc@live.com'
},
{
url: 'turn:192.158.29.39:3478?transport=udp',
credential: 'JZEOEt2V3Qb0y27GRntt2u2PAYA=',
username: '28224511:1379330808'
},
{
url: 'turn:192.158.29.39:3478?transport=tcp',
credential: 'JZEOEt2V3Qb0y27GRntt2u2PAYA=',
username: '28224511:1379330808'
}
];[/code:jxuinrqm]