I’m testing cisco IP phone SPA303 against Asterisk 22.214.171.124.
I’m facing a strange problem that sometimes I can hear only initial part of the first prompt when making an outbound call from SPA303 to a landline through a SIP provider, but sometimes I can hear the entire prompt (about 20 seconds long).
According to wireshark, in those cases where I heard the whole prmopt, asterisk always stayed between the end-points for RTP traffic. And in other cases where I heard only the partial prompt, asterisk didn’t always stay between the end-points for RTP traffic and the problem happened when those both end-points tried to talk to each other directly.
Any idea what might be causing this problem? Thanks.