ISDN GW - ISDN to ISDN Toll Fraud

[RAMEEZ RAHIM]

Hi

I have a 8321 ISDN GW and have the following possibility of toll fraud.

I am dialing in to the Auto Attendant of the ISDN GW from a ISDN endpoint and i am able to dial out back to the ISDN from the Auto-Attendant and connect calls.

If my ISDN Gateway is in India, anonymous user from India can dial in to my ISDN GW Auto attendant and then dial any ISD number and ride on my ISDN network.

I believe, calls initiated from ISDN GW Auto attendant, is matching the IP to ISDN rule and is able to successfully connect the call.

Is there a way i can prevent this from my ISDN GW.       

[Nick Halbert-Lillyman]

You need to change your dial rules so that it only matches your internal dial plan.

[Martin Koch]

Please always mention how you deployed the devices (like cucm, vcs, ...)

some thoughts in general:

* block the loop in the call controll

* disable the auto attendant

* block outbound calls on the ISDN line

* only allow specific destinations

* ...

There were some posting around this in this forum before, plese use the search to look them up.

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[rasimyigit]

How do you call out, if you are on the Auto attendant of the ISDN GW ?

Sent from Cisco Technical Support iPhone App

[Martin Koch]

The auto attendant receives a number, this number will be used to place a new call.

If you use a number which is known by your call control to be placed out via the ISDN

GW again it will cause costly trouble.

Thats why this hairpinned calls needs to be blocked.

Please remember to rate helpful responses and identify helpful or correct answers.