Authorization by Proxy to Gateway

[Roman Rybalko <resiprocate@xxxxxxxxxxx>]

Hello people,

I have the following setup:
UA -> Proxy -> Gateway

Proxy (repro) and Gateway (CommuniGate) require Authentication. User 
Agent (CSipSimple/Snom720/Linphone) can keep credentials for a single 
realm only. Proxy & Gateway require different credentials in different 
realms.

How may I supply credentials for Gateway by Proxy(repro)? Does anyone 
know an existing plugin or a configuration to achieve this? I tried to 
add a Gateway's credentials to /etc/repro/users.txt but it seems to me 
repro does not use them. Another question is: how would I specify which 
user should be used for authentication to Gateway if I have several ones?

--
Regards,
Roman Rybalko