in a thread on realtime multimedia I wrote
Tor, the underlying tech for the AP hide-my-ip feature, doesn’t carry UDP, it’s TCP only [^1]
and in a common config you’ll use UDP for the RTP part (audio stream) of VoIP, as datagrams are a better fit for voice communication (latency more important than every packet delivered).
Some SIP parts are TCP, but not the voice stream. I think there exist TCP based audio communication, WebRTC can do it as fallback if I’m not mistaken, but not the classic SIP/RTP VoIP stack by my current knowledge.
So anyway, disable the Tor part in Advanced Privacy if you use this kind of IP based telephony.
[1] (there are spec proposals for tunneled UDP over TCP though).