MTNL FTTH Mumbai has call receiving issue

Messages
4
Location
Mumbai
ISP
MTNL
I have recently migrated from copper line to FTTH in MTNL Mumbai. I find internet is very stable while I am not receiving telephone call. If I call then it is completely noise free. If my number is called then the connection is not made. Any handle to resolve the issue? Thanks in advance.
 
Messages
28
Location
india
ISP
Airtel
What is the model no. of your ONT ?
 
Messages
4
Location
Mumbai
ISP
MTNL
@bigbyte.me sorry for the delay. My ONT is Syrotech made SY-GPON-1110-WDONT. At present, I find net is good, receiving call is also good while I am unable to receive any call. If anyone calls me, or I call from any other MTNL phone or mobile phone, call does not materialize. Call receiving is now problematic.