I decided to use Extension Routing module instead of not supported now Custom contexts.
I noted one strange thing, when I edited the Additional Settings field in Outbound Routes. My numbering plan contains numbers such 111 and 0111 for example, and if I indicate number 111 in Allowed Extension and click Submit, in the Allowed Extension field appear both 111 and 0111 numbers. Is it a bug? I don't need that the number 0111 has permit on this route, but i can't exclude it from this field while number 111 exist there. I seem that program code considers the both extensions equal. If I forbid using the route for extension 0111 in Extensions-Other, will it solve my problem?