[Serusers] SIP and ATA-186 forwarding

[Mike]

I'm trying to get SER to work properly with the call forwarding feature of
an ATA-186.  The ATA-186 forwards calls (#90number#) by doing a BYE with
an "also" header.  SER doesn't seem to do anything with this at all, and
the call just sits in limbo until everybody hangs up.

Call forwarding on busy/no-answer works, but I think that's because the
ATA is doing a refer instead.

Any clue where I should be looking for this?  Is SER supposed to support
this BYE/also method, and I have something misconfigured, or is there
additional work that needs to be done to support this?

Thanks!

- Mike