After migrating the IP Phones, they are not working or not able to make calls.

IP Phones behind routers not working after migrating

If the phones are showing "connecting", in most cases this is likely because IP phone registration is not complete.

1. IP Phones should ideally get an IP from DHCP servers configured in SSR.

2. Once DHCP DORA is completed, IP phone ideally get DHCP Offer with Custom 242 Option which will have SIP server , HTTP Server IP, Port etc..

• SIP server is where IP phones will connect to, for any registration
• HTTP Server is where IP Phones will connect to, for any firmware upgrade.

3. Once registration process is completed, The IP phones will be shown connected and you will be able to make calls.

If incase of any issues in above process, Alternate option is to try assigning a manual IP to the phone and see if registration is going well and getting connected.

A successful SIP call flow looks like below. please note screenshots are with sample captures available publicly so IPs might not match.