Hi ,
my name is Kamal Zaouli and im a VoIP system integrator for small and large traffic,
due to SIP blocking, you need a proxy server converter, telephony usage will be on a web browser connected to your PBX system instead of softphone (Zoiper) ,
please contact me if interested, a demo is available to test from your new office in egypt ,
Thanks .
Kamal Zaouli