Dear Community.
We have a problem (tm): At some sites, WiFi Calling works, at others it
does not. Sometimes it's dependent on the provider, e.g. Sunrise&Salt
works, Swisscom does not. At another place, Salt&Swisscom works, but not
Sunrise.
Does anyone know when a mobile devices decides that WiFi calling is
possible? Which ports/protocols/... are used? What are the addresses of
the endpoints? How do the probes work? Are there any specific, other
requirements, such as: geolocation, RIPE DB entries, ...? Does anyone
know of a decent technical spec?
I've seem some IPSEC tunnels and read draft-pularikkal. But there seems
to be much more.
The issues are not device dependent, the used device (and subscriptions)
do support WiFi Calling, and are able to use WiFi calling at "some" places.
Best regards
wiwi