Hello,

I was able to locate your ticket and a call sample, it appears that one of our upstream carriers has enabled compact SIP headers -- and we are not receiving an ACK from your UAC after the call connects. We've temporarily disabled this carrier and are looking into mangling the compact headers back into their original form as it is likely that your UAC may not support compact headers due to its failure to respond. Let me know if your issues are not now resolved, thanks!