[OpenSER-Users] interconnect with another operator trough sip

Hi, The architecture looks like this: PSTN <-> AS5300 <-> openser(non_tls) <-> IP-PBX's (asterisk) ^ ^ ^ billing^ (radius) i want to interconnect with another operator trough sip. i think about two methods: -using AS5300 -directly to openser. what method do you recommend for me? and how do you think it's resonable to instal another openser with tls wich will function like session border controller for interconnections with operators through sip. The goal is to not change the architecture of billing and existing SIP proxy. i've read something on the sipforum but i am interested if someone has some experience in such cases, taking into consideration that fact that operators use different equipment that supports sip. i mean that i want in result something like this: | | PSTN <-|-> AS5300 <-> | ^ openser(non_tls) <-> IP-PBX's (asterisk) SIP <-|-> openser<-> ^ | ^ ^ | ^ billing^ (radius)