[asterisk-users] problem with redirects

[Ricardo Carvalho]

Dear all,

My architecture is having some problems with redirects. In the following 
diagram is shown a simple erroneous test. When someone dials from the 
PSTN, signalling of the incoming call is passed to Asterisk which routes 
to SIP Express Route (Ser), and then Ser routes to the phone. The user 
has configured the phone to forward all calls to another PSTN number, 
and then, a "302 Moved Temporarily" reply goes back to Ser which 
forwards back to Asterisk. Because Asterisk is configured with 
promiscredir=yes, it sends a reINVITE to the number announced in the 302 
message as expected, and then that new INVITE goes back to Ser. Ser 
looks at the called number in that INVITE and because it is a PSTN 
number, sends the call back to Asterisk so this gateway can route it to 
PSTN.
Because Asterisk receives the last INVITE with the same Call-ID that he 
passed to Ser in the anterior INVITE, he thinks it's a loop, and ends 
the communication with a "482 Loop Detected" message.
How can I configure Asterisk so that he can route the last INVITE to 
PSTN without giving me that error?

PSTN               Asterisk                   Ser                     UAC
|        INVITE        |                       |                       |
| ------------------>  |                       |                       |
|      100 Trying      |                       |                       |
| <------------------- |                       |                       |
-------------------------------------------------------------------------
|                      |         INVITE        |         INVITE        |
|                      | ------------------>   | ------------------->  |
|                      |       100 trying      |       100 trying      |
|                      | <-------------------  |                       |
|                      | 302 Moved Temporarily | 302 Moved Temporarily |
|                      | <------------------   | <-------------------  |
|                      |           ACK         |           ACK         |
|                      | ------------------->  | ------------------->  |
-------------------------------------------------------------------------
|                      |         INVITE        |                       |
|                      | ------------------->  |                       |
|                      |      100 trying       |                       |
|                      | <-------------------  |                       |
|                      |         INVITE        |                       |
|                      | <-------------------  |                       |
|                      |   482 Loop Detected   |                       |
|                      | ------------------->  |                       |
|                      |           ACK         |                       |
|                      | <-------------------  |                       |



Thanks in advance,
Ricardo.