Thank you all for your suggestions. I followed Hope's suggestion & enabled a new dial plan for the users that must have restricted access. This worked well. Now I have time to examine why the other SIP drops the calls @ :58 seconds. I actually don't need this SIP, but I am curious to find out why it ...

1. Brekeke Product Name and version: Brekeke OnDO SIP Server for OnDO PBX Version 1.5.3.0 2. Java version: J2SE 1.5.0 3. OS type and the version: XP Pro SP2 4. UA (phone), gateway or other hardware/software involved: X-Lite & Linksys SPA941 5. Select your network pattern from http://www.brekeke-sip ...