[asterisk-users] Unique call ID's across several systems

[Steve Edwards]

On Sat, 21 Oct 2006, Jeremy McNamara wrote:

> Steve Edwards wrote:
>> I have a farm of 7 1u's) with te410p's. When a call comes in, I call an AGI 
>> that creates a channel variable named GLOBALID. The GLOBALID is 2 digits 
>> for the host number, 2 digits for the channel number, and 8 characters for 
>> the UNIQUEID encoded in hex.
>> 
>> Then, I stuff it into CALLERID(name) so it will be available as the call is 
>> sent (using dial()) to the application servers.
>
> AGI is not going to scale.  Why not do it all with dial plan logic? Store a 
> global system id for each system and concat it onto the uniqueid CDR value.

Our need for a globalid (in addition to our needs) was mandated by our 
credit card processor. They also limited us to length, upper case letters 
and digits -- not even a lowly period was acceptable to them :)

To fit the host, channel, and unique id in I decided to encode the unique 
as hex. This system was designed before dialplan functions and I didn't 
see an easy "dialplan way" to encode to hex, so I cranked out an AGI.

I don't know how fast a dialplan implementation would be (if a hex 
function was available), but I benched the AGI approach and the server 
does 1,000 in about 4 seconds.

I'm sure your knowledge of telephony far exceeds mine, Jeremy. For a 
system with only 92 channels can the telco deliver more than 92 calls in 
0.4 seconds over PRI?

The average call duration for this system is about 10 minutes, so the 
probability of all 92 channels being free at the same time is rather 
small.

I always wondered how much overhead invoking an AGI incurred. Setting up 
the AGI environment, spawning a new process, parsing the AGI environment, 
doing something useful, terminating the AGI process -- it sounds like it 
would take forever. Now I know it only takes about 40 msec.

Thanks in advance,
------------------------------------------------------------------------
Steve Edwards      sedwards at sedwards.com      Voice: +1-760-468-3867 PST
Newline                                             Fax: +1-760-731-3000