Funnily enough, most people install phones with BLF lamps, on install something like hudlite/FOP/etc so you know if the person is on the phone before you call them..

PaulH


> Daniel Johnson <dan.j@scanningsystems.com.au> wrote:
> 
> Hi,
> 
> I am trying to implement the callback feature of our old phone system. 
> This feature may go by a different name in asterisk?
> 
> It worked as follows. If phone A called phone B and it was BUSY, you 
> press a button to enable a callback.
> User A is free to continue work or make other calls.
> What this meant is that when both phones became free, phone A would 
> ring, on answer it would call phone B automatically.
> 
> Here is how I have tried to achieve this with asterisk.
> 
> When A calls B and B is busy you get a menu, 1 to set callback and 2 to 
> leave voicemail.
> The set of the callback is done via AGI call to PHP script to set the 
> details in MySQL DB.
> 
> On all call hangups I check to see if there is a pending Callback via 
> another AGI script.
> The script sets a couple of variables which I check in my Dialplan. If 
> there is a callback pending for the
> phone that just hung up, I need to check that the other phone involved  
> is FREE. This is what I can not get to work.
> 
> I have tried ChanIsAvail which does not appear to work.
> I have hints setup for each SIP phone. Which would be perfect, however 
> it does not appear that you can check the HINT STATE in the dialplan.
> I have done plenty of googling and have found this 
> http://bugs.digium.com/view.php?id=10635 which appears that this kind of 
> 
> functionality was placed in 1.4.11. (DEVICE_STATE(), EXTENSION_STATE())
> I have 1.4.21.2 and do not have these features.
> 
> To continue with the rest of the feature. If the ChanIsAvail says all is 
> 
> good. I then launch another AGI to write a CALLFILE and remove the 
> pending callback request from the DB.
> This all works if A is not busy when B finishes their call etc.
> 
> I am sure that others have implemented this kind of feature. If you 
> could share your implementation or give me some pointers or even the 
> correct asterisk name so I can google and get the help I need, that 
> would be great.
> I am considering trying out 1.6 which should have these features, 
> however not sure if stability is going to be a problem.
> 
> I have based my implantation based of a previous message to the list:
> 
> On Tue, Jun 10, 2008 at 5:34 PM, Phil Knighton <phil.knighton@mjog.com> 
> wrote:
> 
> > > Hello
> > >
> > > I'm looking for a way to do the following using my Asterisk system 
> and Snom
> > > SIP phones...
> > >
> > > Scenario:
> > >
> > > Caller on Internal Phone 1 calls internal phone2.  Phone 2 is busy 
> (or more
> > > accurately goes straight to voicemail).
> > > Caller on internal phone 1 can press a button / dial a code 
> (explained in
> > > next step) and hangup
> > > When phone 2 is free, phone 1 rings and on answer dials phone 2
> > >
> > > I was sure this was called "camping" - but all the camping stuff I 
> can find,
> > > refers to the caller having to hang on the phone and wait.  Am I 
> missing
> > > something?
> > >
> > > Anyone have a solution?
> > >
> >   
> 
> Quick solution that comes into mind:
> 
> Set(exten_copy = ${EXTEN});
> Dial(SIP/${EXTEN})
> if ("${DIALSTATUS}"="BUSY") {
>   // prompt for camp
>   Set(DB(camp/${EXTEN}/call_to)=${CALLERID(num));
> }
> 
> h => {
>   Set(call_to=${DB(camp/${exten_copy}/call_to)});
>   if ("${call_to}"!="") {
>     Set(DB(camp/${exten_copy}/call_to)=);
>     System(call_to ${exten_copy} ${call_to});
>   }
> }
> 
> So, in case if phone2 is busy, store callerid of phone1 in database,
> so when phone2 will hangup it will triger a script "call_to" which
> however can originate call trough manager or call-file.
> 
> Of course you will need some additional handling in case if multiple
> callers decide to camp, or diferent protocols are used, etc.
> 
> Regards,
> Atis
> 
>  
> 
> Thanks in Advance for any help.
> 
> Regards
> 
> *Daniel Johnson*
> Systems Administrator / Systems Development
> Scanning Systems Australia
> 
> Scanning Systems Australia
> 
> *Office:* +61 7 3387 5555
> *Facsimile:* +61 7 3387 5588
> *E-mail:* dan.j@scanningsystems.com.au 
> <mailto:dan.j@scanningsystems.com.au>
> *Website:* http://www.scanningsystems.com.au