All of our outgoing calls are not showing caller ID when using our main SIP trunk line. I contacted the SIP provider and they said that the From headers are not sending to them correctly. I did a packet capture and it showed 3CX was sending the SIP From: header as From: "403XXXXXXX"<sip:216.13.193.XXX:5060>; The SIP provider said that the From header should look like From: "403XXXXXXX"<sip:403XXXXXXX@216.13.XXX.XXX:5060>; When I tried with another SIP trunk provider, the caller ID showed up correctly. From the packet capture of that call, the From header was sent as From: "403XXXXXXX"<sip:403XXXXXXX@vancouver2.voip.ms:5060>; We are using 3CX v15 with SP4. Our main SIP trunk provider is Allstream, the second SIP trunk provider is Voip.ms. I made sure that the outbound parameters for each SIP trunk are the same. The only difference is that Allstream is IP based authentication, and Voip.ms is account based authentication. Anyone has any ideas on why this is happening?