call internal

1. Brekeke Product Name and version:
server-product Brekeke SIP Server
server-ver 2.1.6.6/239

2. Java version:
1.6.0_07

3. OS type and the version:
Windows 2003

6. Your problem:
how to set dial plan? if i register as 1234, and other register as 6789. i want call to 6789 ( like hotel PBX , call internal not call outside,)

It is a lack of information.. Also, it seems you didn't read the document.

Can a SIP client make a register to the SIP Server?
If so, you don't have to use the dialplan.

If you want to create the dialplan. Read the dialplan tutorial.

what kind of SIP client are you using??