asterisk users - Nov 2007 - SLA: Handling of errors in outgoing call

Hi All.

I've been experimenting with SLA on Asterisk 1.4.13 (patched up to
1.4.14).

I am using a SIP channel for my "trunk" line.

On the whole things are good, but I have noticed that if I misdial an
outgoing call,
i.e. I get 404 "Not Found" in the SIP trace, then the trunk line just
drops, rather than
presenting an error tone or message to the user.

=======================
Here is my sip.conf (cleaned to protect the innocent):

register => 5000:password:username at vsp5000/5000

[vsp5000]
type=peer
secret=password
username=username
host=vsp.ip.address
fromuser=5000
fromdomain=vsp.domain
canreinvite=no
context=line-in
insecure=very

=======================
Here is my sla.conf:

[line1]
type=trunk
device=Local/disa at line1_outbound


[station](!)               ; When there are a lot of stations that are
configured the same way,
                            ; it is convenient to use a configuration
template like this so that
                            ; the common settings stay in one place.
type=station
autocontext=default
trunk=line1
trunk=line2 
;trunk=line3
;trunk=line4 

[station1](station)
device=SIP/station1

[station2](station)
device=SIP/station2

=======================
Here is my extensions.conf:

[macro-call-sla]
;	${ARG1} - line name
exten => s,1,SLATrunk(${ARG1})
exten => s,2,Hangup

[line1_outbound]
exten => disa,1,Disa(no-password|line1_outbound)
exten => _XXXX,1,Dial(SIP/${EXTEN}@vsp5000)
exten => _XXXX,2,Hangup

[line-in]
exten => 5000,1,Macro(call-sla,line1)

=======================
So to summarise:
	if I seize the line and dial a number known at vsp5000 then I
get ringing etc - good.
	if I seize the line and dial a number unknown at vsp5000 then
the call drops silently - not good.

Any ideas?


__________
Steve Langstaff

Steve Langstaff wrote:
> [line1_outbound]
> exten => disa,1,Disa(no-password|line1_outbound)
> exten => _XXXX,1,Dial(SIP/${EXTEN}@vsp5000)
> exten => _XXXX,2,Hangup
> So to summarise:
> 	if I seize the line and dial a number known at vsp5000 then I
> get ringing etc - good.
> 	if I seize the line and dial a number unknown at vsp5000 then
> the call drops silently - not good.
Your issue is actually in the [line1_outbound] context that I have quoted above.
 Here is what happens:

As far as Disa() is concerned, any 4 digit number is a valid extension.  Once
you dial something (whether is valid at the other end or not), the call goes on
and executes Dial().  However, since the number you have dialed is not valid,
Dial() immediately returns and then Hangup is executed.  That is when the call
is dropping.

So, I can think of a few different ways to solve this issue.  The first couple
involve using an IAX2 or DUNDi switch statement in the line1_outbound context.
That would allow Asterisk to query the remote server as to what extensions are
valid.  However, I won't get into the details of how that is configured
right
now ...

The other alternative is to solve it in the dialplan, with something like this:

[line1_outbound]
exten => disa,1,Disa(no-password|line1_outbound)
exten => _XXXX,1,Dial(SIP/${EXTEN}@vsp5000)
exten => _XXXX,n,Congestion
exten => _XXXX,n,Wait(10) ; Give Congestion for 10 seconds
exten => _XXXX,n,Hangup

You could improve this even further by checking the DIALSTATUS and playing
different tones, or just hanging up, accordingly.

I hope this helps,

-- 
Russell Bryant
Senior Software Engineer
Open Source Team Lead
Digium, Inc.