Hello,
Several users of
iptel.org are using Draytek phones. Those phones are
broken -- they are constantly flooding our server with REGISTER messages
even if they got 200 OK (and the expires value is long enough).
If you have such a phone please don't use it and ask the manufacturer to
fix it.
If you have direct contact to Draytek engineers (not technical support),
please mail it to me.
Jan.