[asterisk-users] distribute free call minutes over different channels

[Eckhard Jokisch]

On Tuesday 24 November 2009 13:10:43 Tzafrir Cohen wrote:
> On Tue, Nov 24, 2009 at 01:07:28PM +0100, Eckhard Jokisch wrote:
> > Hi,
> > I have 4 ISDN channels (2 lines) and each line may do calls of up to 360
> > minutes/month for free.
> > As I understand asterisk will pick the first available line so the
> > probability is big that the other lines will not use their free minutes
> > and the firs line will exceed the free minutes.
> 
> If you use chan_zap or chan_dahdi, you can use r/R instead of g/G to go
> round-robin through the channels rather than start from the first/last
> (respectively). This would give you a rather even spreading of the
> outgoing calls.
> 
I tried like this:
exten => _0.,1,Dial(msidn/r:extern/${EXTEN}:1)

where "extern" is the chapter in the misdn.conf that looks like
[extern]
ports=1,2,3,4
context=isdn
msns=*


But this does not work at all. Asterisk can not setup a channel.
What would be the right syntax to invoke round robin in Dial command?

BR
Eckhard