I have this case:
My device Linksys-WRTP54G is connected to ADSL modem & running well with SIP Mobile phones through it the mobile phone is directly registered and connected calls are done with no problems.
But if I connect any type of ADSL modem with built-in integrated router (Modem and Router in the same unit device),SIP Mobile phones are directly registered and connected â¦. But the caller person doesn't hear ring back tone and called person doesn't hear the voice for caller personâ¦. Do you have any ideas?