Local Sip port on T46

[JamesC]

We have disabled 1 of the 2 accounts and tested for a couple of hours and everything seems fine, no problems so far.

Analyzing the issue a little further showed that when we enable account 2 this account only receives incoming calls when account 1 is idle. When account 1 is calling, the PBX gets a 486 from account 2 when trying to offer a call to it.

Enabling account 2 also gives re-register problems after a couple of hours (all random; sometimes 3 hours, sometimes 6 and so on...).

What we have done so far:
- replaced utp cable
- replaced power adapter
- upgrade to latest firmware
- deleted both accounts and created them again in PBX
- deleted both accounts and created them again in the phone
- placed a Cisco 504 and a Linksys SPA942 at the users desk with same accounts and this works fine

What else can this be? We really suspect the local SIP port as both accounts map to the PBX with port 5060.