But before I detail the problem, let me describe my environment:
Cisco 2951 Integrated Service Router with 8.6
Cisco IP Phones 6921, 7942, 7962.
PSTN using an ISDN PRI line with 30 channels.
GSM card for mobile calling
So here is my problem:
When I make a call mobile call (using the GSM card), the phones start to count the durations of the call and that register is sent through the CDR files and the Stonevoice Application Suite 2012 (Billing software) considers this as a “successfully made call”.
See the pictures bellow:
I HAVE, ON THIS PIC, THE IP PHONE 6921:
I make a mobile call to my number: 82xxxxxxx - 82 is a mobile operator here in Mozambique (mCel).
AND I DON'T PICK UP THIS CALL, but the durations starts counting. See the pictures:
Note: What is on a green box is my number, on the red box is the call duration.
So, looking for this call record on Stonevoice Application Suite 2012 for billing, I FIND IT:
Note: See the red box, the green arrow and the info on the picture:
The made call WITH NO PICKING UP is charged because of the duration sent through CDR to Stonevoice Application Suite 2012.
So, how can I insure that the duration counting process ON MOBILE CALLS starts exactly when the other person picks up the phone?
Is this possible?
Is important to say that when I make a call through a fixed line (using PSTN or Direct Inward Dialing - DID) I don’t have this problem.
Normally FXO/FXS does not provide answer supervision (check if your GSM box supports battery-reversal), that means the router cannot know if the call has been answered or not, so it assumes the call is connected as dialing ends.
You can try 'supervisory answer dualtone sensitivity', voice voice-activate answer supervision but that is know to be unreliable.
In conclusion, if you want reliable answer (and disconnect) supervision for GSM box, you need to use ISDN BRI, or SIP interface, not FXO.