Dear 3CX support, I have a problem calling an IP extension from Dialogic softIP via a 3CX IPBX. Calling from a softphone (xLite, SJPhone) to the same extension via the IPBX doesn't show this issue. The difference I could spot is that the URI in the Proxy authorization contains a port number in the softIP case, whereas it doesn't appear in the softphone case. softIP: Proxy-Authorization: Digest username="15",realm="3CXPhoneSystem",nonce="12885495263:cc2ff266f96698b98eee1b6bd96f7479",uri="sip:firstname.lastname@example.org:5060",response="a95f1720494b5373f9783664e2de12fe",algorithm=MD5 xLite: Proxy-Authorization: Digest username="15",realm="3CXPhoneSystem",nonce="12885495307:7fbd64b6dbdba93c5cc81d7ccc294f48",uri="sip:email@example.com",response="ed5292b664fafbf8eeaffe889affe9c7",algorithm=MD5 This might not be the reason why softIP receives a 404 in response, I have attached a wireshark trace so you can tell me if the problem comes from somewhere else. The first call in the trace is from softIP, the third one is from xLite. Can you tell me why the request is rejected? Is there any in-depth debug logging on the IPBX that could show why this is failing? Could the port be ignored when parsing the URI? Thank you for your support.