Our setup involves a Sip softphone registering with a fresh install of
Asterisk v188.8.131.52 through an outbound proxy (Kamailio v3.1.1).
We observe that about 80% of the time, immediately after startup of the
softphone, when the softphone sends a REGISTER message, Asterisk replies
with a “503 Server error”. However, subsequent REGISTER messages are
replied to appropriately (with a 401 Unauthorized).
There are very few devices (under 5) registered with Asterisk, so this
is not an overload issue.
Please find attached a SIP trace for device registration.
– What might cause this behavior in Asterisk ?
– Are there any config file parameters that require to be changed ?
– Would it help to see any other specific logs, if so which ones ?