Thanks for your reply. I already understood what issue was. Appeared that RP does not support UDP SIP. It is only support TCP SIP. It was easy as you see. Do you have any plan to implement SIP UDP in RP? Nope we plan to use RP to register SIP phones .Some phones does not support TCP SIP. But SIP UDP supported by all of them. With providers we have direct links which does not require it (i mean RP functionality).

Basically we plan to use it like :

Customer PHONE -> internet -> RP on COLO -> HOSTED PBX (IPVA)-> OUR infrastruct -> TERM PROVIDER.

Such schema does not described anywhere in your wiki but for sure it works . Almost works.