Asterisk Server sending 503 to the Open-IMS Core back

Hi Team,

I am facing problem when I am integrating Asterisk Sip server with Open IMS Core in our lab premises.

I have defined the iFC in IMS Core for Asterisk and also given IMPUs and IMSIP related information in Asterisks Extension.conf and Sip.conf file.
The moment INVITE goes from IMS to Asterisk server, Asterisk SIP Server responds with 503 Response and call get disconnected.
Please help me, how can I resolve this issue.

If any more information you topple need on the same, please in touch with me on my official mail id :

With Best Regards,
Dharmendra Dwivedi

Asterisk logging, please. This should have been asked on Asterisk Support.