sipXpbx - Unable to call other extensions

I have installed sipXpbx 3.4 on CentOS 4.3 version. Everything went OK. After completing the install, I added, users, devices (Polycom IP 601 and AASTRA 48i IP Phones) and assigned Lines to these phones.

I get the dial tone on both the phones, and it goes to the AA when I press "0", and also they individually go to the Voicemail system and record names and greetings.

BUT - None of them can call each other by extesion numbers. I have two extensions setup, 200 and 201.

On the sipXpbx Config menu, I do not see anything under the Registered tab.

Any kind of help is very much appreciated in advance.

Are the phones registering?

In the UI Check under #Diagnostics>Registrations and see if the sip address is registered.

My bad. I didn't read the whole thing.

Make sure your internal calling dial plan is enabled.