I have the following asterisk configuration (sip.conf) : [General] externip=82.79.81.3 localnet=192.168.10.0 localmask=255.255.255.0 [Phone1] type=friend host=dynamic nat=yes qualify=yes context=sip callerid="Phone1" <1> disallow=all allow=gsm [Phone2] type=friend host=dynamic qualify=yes context=sip callerid="Phone2" <2> disallow=all allow=gsm [Phone3] type=friend host=dynamic nat=yes qualify=yes context=sip callerid="Phone3" <3> disallow=all allow=gsm [Phone4] type=friend host=dynamic nat=yes qualify=yes context=sip callerid="Phone4" <4> disallow=all allow=gsm I use the following extensions for asterisk (extensions.conf): [sip] exten => 1,1,Dial(SIP/Phone1,20,tr) exten => 2,1,Dial(SIP/Phone2,20,tr) exten => 3,1,Dial(SIP/Phone3,20,tr) exten => 4,1,Dial(SIP/Phone4,20,tr) This Asterisk PBX configuration work with X-Lite softphone. I have more X-Lite clients and all use Windows XP. Phone 1 = Yo2lux (my phone number) - Windows XP box Phone 2 = Mike - Windows XP box Phone 3 = Bob - Windows XP box Phone 4 = Theo - Windows XP box Phone 2, Phone3 and Phone4 now turned off, only Phone1 PC turned on : Phone 1 = Yo2lux (Turned on) Phone 2,3,4 = Mike, Bob and Theo ( This 3 PC now turned off) I have a strange problem: I call Phone2 and don't answer. Ok, the pc is turned off I call Phone3 and don't answer. Ok, the pc is turned off I call Phone4 and answer (turned off pc). I get an answer from Phone number1. But im not registered as Phone1 at Phone4. Any idea to solve this problem ? Thank you very much !