[Serusers] can't login using MSN messenger 4.6

Hi All I've just installed ser server...seems to running ok, but when i try to log in via MSN messenger, it doesn't connect. ngrep shows this [root@jmay-csx root]# ngrep -n 5060 -d eth0 andy interface: eth0 (156.151.96.0/255.255.254.0) match: andy ############################################################################ ############################################################################ ######################################################### U 156.151.96.136:1299 -> 156.151.97.201:5060 REGISTER sip:portal.com SIP/2.0..Via: SIP/2.0/UDP 156.151.96 .136:9924..Max-Forwards: 70..From: <sip:andy@portal.com>;tag =e7de21b1a54048f596a97a803e62a092;epid=3e95aa3126..To: <sip: andy@portal.com>..Call-ID: 907cde0319b64cba8b1dd03f75ce90a9@ 156.151.96.136..CSeq: 1 REGISTER..Contact: <sip:156.151.96.1 36:9924>;methods="INVITE, MESSAGE, INFO, SUBSCRIBE, OPTIONS, BYE, CANCEL, NOTIFY, ACK, REFER"..User-Agent: RTC/1.2.4949. .Event: registration..Allow-Events: presence..Content-Length : 0.... ######### U 156.151.97.201:5060 -> 156.151.32.148:5060 REGISTER sip:portal.com SIP/2.0..Record-Route: <sip:156.151. 97.201;ftag=e7de21b1a54048f596a97a803e62a092;lr=on>..Via: SI P/2.0/UDP 156.151.97.201;branch=z9hG4bKae7d.a118d8e6.0..Via: SIP/2.0/UDP 156.151.96.136:9924..Max-Forwards: 69..From: <s ip:andy@portal.com>;tag=e7de21b1a54048f596a97a803e62a092;epi d=3e95aa3126..To: <sip:andy@portal.com>..Call-ID: 907cde0319 b64cba8b1dd03f75ce90a9@156.151.96.136..CSeq: 1 REGISTER..Con tact: <sip:156.151.96.136:9924>;methods="INVITE, MESSAGE, IN FO, SUBSCRIBE, OPTIONS, BYE, CANCEL, NOTIFY, ACK, REFER"..Us er-Agent: RTC/1.2.4949..Event: registration..Allow-Events: p resence..Content-Length: 0.... ############################################################################ ##### U 156.151.96.136:1299 -> 156.151.97.201:5060 REGISTER sip:portal.com SIP/2.0..Via: SIP/2.0/UDP 156.151.96 .136:9924..Max-Forwards: 70..From: <sip:andy@portal.com>;tag =e7de21b1a54048f596a97a803e62a092;epid=3e95aa3126..To: <sip: andy@portal.com>..Call-ID: 907cde0319b64cba8b1dd03f75ce90a9@ 156.151.96.136..CSeq: 1 REGISTER..Contact: <sip:156.151.96.1 36:9924>;methods="INVITE, MESSAGE, INFO, SUBSCRIBE, OPTIONS, BYE, CANCEL, NOTIFY, ACK, REFER"..User-Agent: RTC/1.2.4949. .Event: registration..Allow-Events: presence..Content-Length : 0.... resence..Content-Length: 0.... what else can i look at...what might be the cause. thaks Andy