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Got a Cisco Sipura SPA 941 hardware phone and I am connected to Asterix (most likely) VoIP server of my provider.
I am behind a firewall (ADSL) and I have put my phone to the DMZ zone, so it should be reachable from the internet.
Now I can make calls without any problems, but when somebody calls me I can hear it ringing, but when I pickup the earphone, nothing happens and I see "Answering Call" on the display. On the other side of the line I still hear its ringing.
Now question to all superuser VoIP experts: what option should I search on my phone to chage to get this working? My friend gave me advice DMTF (got Auto), tried all options without any luck.
Many thanks for tips. I know what is intrusion detection, not sure about ALG, SPI. Will try to find that on my router. My ISP tells me to open the following ports: TCP a UDP 5060, RTP 10000-20000 – lzap – 2011-08-15T11:17:28.047
So I found ALG section there, I only have "SIP" enabled there. So according to your advice I am disabling it right now. There's also intrusion thing ("Enable DOS and Portscan Protection") but I have it turned off. – lzap – 2011-08-15T11:22:00.193
I CANNOT BELIVE IT BUT UNCHECKING THE "SIP" OPTION HELPS! MANY THANKS! THANK YOU THANK YOU THANK YOU :-) – lzap – 2011-08-15T11:33:03.060