I have an issue with my Cisco SPA303 VoIP phone. It seems I can make outgoing calls fine but if I get an incoming call, the phone rings and I answer but there is silence - no voice coming through and apparently they cant hear me either. Is it a firewall issue? I did notice a setting for mapped SIP port per extension, should I be mapping these through my router? I'm asking before I do this because I have had these phones for a while and never had this issue before...
Thanks in advance