Is there something special in connecting a 1.2 and 1.4 systems??? I have connected a number of 1.2 systems using SIP between them and had no issue. In this case I am getting "407 Proxy Authentication Required" I did the same steps I did for 1.2 Basically I have entries in sip.conf on both machines with the IP pointing to each other. [x_to_y] type=friend username=x_to_y secret=yes host=25.x.x.x context=x_to_y allow=ulaw allow=alaw <--- Reliably Transmitting (no NAT) to 25.x.x.x:5060 ---> SIP/2.0 407 Proxy Authentication Required^M Via: SIP/2.0/UDP 25.x.x.x:5060;branch=z9hG4bK7d55a70d;received=25.x.x.x;rport=5060^M From: "528 528" <sip:528 at 25.x.x.x>;tag=as7855961b^M To: <sip:59 at 192.168.1.59>;tag=as0ab59997^M Call-ID: 19cf6bb2489f81bc765e5d194e121348 at 25.x.x.x^M CSeq: 102 INVITE^M User-Agent: Asterisk PBX^M Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY^M Supported: replaces^M Proxy-Authenticate: Digest algorithm=MD5, realm="asterisk", nonce="49cd7fc3"^M Content-Length: 0^M THanks, Jerry