I am running an Asterisk PBX 11.6-cert10 with about 20 SIP phones and recently one of the phones
(Snom 720) always returns “486 Busy Here” when calling anonymously. It’s only a single phone, the rest works as expected. I checked the phone’s settings and there are no differences in the configuration compared to the rest.
I do not expect that Asterisk is the problem, but does someone know under which circumstances this kind of problem can occur?