Good morning,
I am Italian and my problem is related to two Cisco SPA 303 I bought during my last trip in US and connected to my Router PBX Fritz!Box 7390, all incoming calls, locals and externals are received in the right way, while for outbound calls, only external calls using the telecom fixed line succeed if I try to call another internal such as FON1 or FON2 I can hear from them but when I speak there is no audio on the other side, I have tested and changed several codecs on the Cisco SPA 303 but they all failed. 2 additional ATA analog phones are connected to the PBX router and they have no problem at all.
Thanks in advance for your support
Giancarlo