Dear Team

i have AC1200 (XC220-G3v)wireless VoIP GPON/EPON router With this router we are able to connect both broadband and VOIP connection. 

Just for FYI, I had a tried to configure a VOIP with valid configurations (BSNL FTTH) and ISP technician also , But from this router the SIP registration always fails with 502 (Bad gateway) and my INTERNET connection working fine.

MY all configuration details are valid as per ISP (BSNL FTTH)

Kindly solve this issue as soon as possible