[Serusers] SER Strange Calling Issue

Hi User ---> SER -----> BroadoSoft -----> PSTN when I send calls to PSTN I'm changing the From to one of BroadSoft users b'coz without that BroadSoft don't allow me to Call PSTN. When call comes to PSTN Route I'm changing the the From : subst('/^From:(.*)sip:[^@]*@[a-zA-Z0-9.]+(.*)$/From:< sip:8233843435@Broadsoft IP>/ig'); calls goes fine to Broadsoft and then to PSTN but, once call connect to PSTN I'm able to hear other side but my phone always shows Calling and other side is not able to hear me (b'coz from my side channel is not getting answered). I tried forcing mediaproxy before PSTN Calls but no luck. Please advise. Its very urgent. Thanks, Arun