I have multiple users of a Free PBX hosted solution who loose calls after the 30 minute mark. I can't find any settings for length of call in the Free PBX software or why this would be happening and can only link it to the Zoiper 5 media we are all using. We have paid for the licenses for Pro users but the calls go for 30-35 minutes and then neither party can hear the other. The call recordings through the system only go through the silence but both parties express that they hear nothing but silence until they end the calls. Any help is appreciated at this point.