I have a hospital client that has a mental health ward. The ward has two phones that are available for patient use (for local calling). However, some patients find it quite amusing to call 911 often to annoy and encumber the public safety dispatchers. I was asked if there was a way to block 911 calls from those two phones only. Should anyone else on this forum have a similar issue, here's the solution that worked in this case:
The ARS digit conversion table was modified so that the digit strings '11' and '911' are deleted and replaced with a digit string that is pointed back to the extension network. That new string is a VDN that points to a vector built just for this purpose. Note: the '11' entry was provided in case a user dials just '911' in haste rather than '9911'.
The vector employs a couple of 'goto step X if ani = Y' steps, where Y is one of the offending stations. Step X disconnects after playing an announcement that says "911 calls are not allowed from this phone. If this is a real emergency, please go to the nurse station." If the calling party is NOT one of the offending stations, then the next step in the vector is a 'route-to number' statement that dials the trunk access code for the appropriate trunk group followed by '911'. Note that the 'route-to' cannot be set to dial '9911' because that would cause an infinite loop through the digit conversion table, ergo the requirement to employ direct trunk group access (which, in turn, requires that the 'Dial Access?" field on page 1 of the trunk group form be set to 'y').
It works!
Additional notes:
- The TACs in this system are very unlikely to be guessed or accidentally discovered (4-digit beginning with zero), so there is no concern about turning on dial access for a trunk group. For systems where enabling dial access IS a concern, an alternative would be to change the vector's route-to digit string to one that points to a fictitious PSTN number, e.g. 95551234. That number would be entered in the ARS Analysis table and pointed to a unique route pattern that deletes the entire number and replaces it with '911'.
- Using CORs to accomplish this objective was impossible because an FRL of '0' or higher is required to dial 911, i.e. no one is prevented from dialing '911' by FRL. We couldn't set the two offending stations to a lower FRL than '0' but even if we could, those phone would then also be prevented from making local PSTN calls, yet that is exactly what they are there for.
The ARS digit conversion table was modified so that the digit strings '11' and '911' are deleted and replaced with a digit string that is pointed back to the extension network. That new string is a VDN that points to a vector built just for this purpose. Note: the '11' entry was provided in case a user dials just '911' in haste rather than '9911'.
The vector employs a couple of 'goto step X if ani = Y' steps, where Y is one of the offending stations. Step X disconnects after playing an announcement that says "911 calls are not allowed from this phone. If this is a real emergency, please go to the nurse station." If the calling party is NOT one of the offending stations, then the next step in the vector is a 'route-to number' statement that dials the trunk access code for the appropriate trunk group followed by '911'. Note that the 'route-to' cannot be set to dial '9911' because that would cause an infinite loop through the digit conversion table, ergo the requirement to employ direct trunk group access (which, in turn, requires that the 'Dial Access?" field on page 1 of the trunk group form be set to 'y').
It works!
Additional notes:
- The TACs in this system are very unlikely to be guessed or accidentally discovered (4-digit beginning with zero), so there is no concern about turning on dial access for a trunk group. For systems where enabling dial access IS a concern, an alternative would be to change the vector's route-to digit string to one that points to a fictitious PSTN number, e.g. 95551234. That number would be entered in the ARS Analysis table and pointed to a unique route pattern that deletes the entire number and replaces it with '911'.
- Using CORs to accomplish this objective was impossible because an FRL of '0' or higher is required to dial 911, i.e. no one is prevented from dialing '911' by FRL. We couldn't set the two offending stations to a lower FRL than '0' but even if we could, those phone would then also be prevented from making local PSTN calls, yet that is exactly what they are there for.
