491 Message

Hi,

Can anybody tell me why Asterisk responds INVITE for call retrival with 491 Request Pending.

Regards,
Chinmoy

UAS Behavior

Section 13.3.1 describes the procedure for distinguishing incoming
re-INVITEs from incoming initial INVITEs and handling a re-INVITE for
an existing dialog.

A UAS that receives a second INVITE before it sends the final
response to a first INVITE with a lower CSeq sequence number on the
same dialog MUST return a 500 (Server Internal Error) response to the
second INVITE and MUST include a Retry-After header field with a
randomly chosen value of between 0 and 10 seconds.

A UAS that receives an INVITE on a dialog while an INVITE it had sent
on that dialog is in progress MUST return a 491 (Request Pending)
response to the received INVITE.

For any Questions refer RFC 3261 .(Refer Section no : 14.2)

Fo