Have had this happen twice with same SIP vendor - Can call in on SIP but cannot call out. SIP vendor says they Invite registration - none is sent from SBX. I am running 4.OAi software and have the VOIB card at 3.0AH firmware. Manipulating entries in the SIP Attrib 2 table is spooky at best. When I got the SIP trunks working again, I deleted my Auth User Name and Password and I could still call out!!! When calls fail the display on the phone shows the elapsed time connected for 4 seconds then error tone. One of the two SBX's is directly on two public IP's off of a Comcast Modem/Router. The other is in our office behind our firewall on two private IP's. Veritcal is scratching their heads - no help. Has anyone out there seen this behavior? Every other dbase entry I have used in the SBX is solid - what you see is what you get. The SIP Attrib 2 table is not stable at all.