[Asterisk-Users] Auto Dial With An Extension number?

[buffalo at icarus.yml.com]

Greetings,

I've been looking through the docs, but haven't located any info on how to 
autodial a number with an extension.

I've got a working autodial set up where I can get asterisk to dial a
number and play a prerecorded message, and ask for confirmation of
receipt. Is it possible to get asterisk to dial a given number, pause for
a few second and then dial an extension number before playing the
prerecorded messages?

Right now I'm generating calls by dropping a file into 
/var/spool/asterisk/outgoing:

----------------
Channel: SIP/617xxxxxxx at broadvoice
Callerid: 240xxxxxxx
MaxRetries: 5
RetryTime: 300
WaitTime: 45
Context: outboundmsg1
Extension: s
Priority: 1
----------------

How would the "Channel:" line need to be modified to allow for dialing 
(for example) 617xxxxxxx, extension 386? Or would I need to do this a 
different way?

TIA for any and all replies/hints/pointers,

--Duncan