Help with setup on a callcentric account

I have installed callcentric and the account registers with my RTP300 box. I would like to set this box up as an extension and route the calls through asterisk. I keep getting the following when Asterisk is running:

Apr 17 16:46:07] NOTICE[305]: chan_sip.c:7715 sip_reg_timeout: – Registration for '’ timed out, trying again (Attempt #12)

Cannot figure out what I am doing wrong. If anyone has successful .conf files that work with this type setup and can help, it would be appreciated.

Also, eventually I would like to set Asterisk up to allow incoming calls and allow me to use a code to dial out from there. Will I need to have two DIDs to accomplish this?