SV8100 - Rapid Busy After 3 Digit Calls Including 911

[FortKnox]

System: SV8100
At my main site, I have a PRI and I can dial 9,511 or 9,611 just fine. I can also call either 9,911 or 911 just fine. Everything normal here.

The problem is at my branch offices where they have CO/POTS trunk lines.
When they dial 911, or 9,911, or 9,511 or 9,611 type numbers, they get rapid busy 5 seconds after dialing the last digit.
They are not using ARS.
However, the calls goes through fine if I terminate all of them with a # - For example, 9,611# works fine.
Its like the system is waiting for more digits to be entered.
This issue was discovered because they needed to call 911, but office staff were met with rapid busy after dialing 911 or 9,911; but police officers came onsite reporting a bunch of ring/hangups.

I have worked with my local NEC authorized dealer, and they have not had any luck figuring the issue out.

A work-around that I discovered works is changing 21-01-03 "External Call Inter-digit Time" from the default of 5 to a value of 0.
This allows the calls to go out, without the system dropping the call 5 seconds after the last digit is entered.

Big kudos to anyone who can figure this one out!!!

 

[belevedere]

Sounds to me like these are not true POTTs lines, but something a cable or internet carrier brought in as SIP and converted through a router. I'd have a word with them about it. However if you are adept enough with ARS (LCR) you can set that up with a max digits setting of 3 for 911 calls. The # is a delimiter essentially telling the carrier that you digit string has ended, send digits dialed, before the time out.

 

[FortKnox]

I know what you are saying about them not being true POTS lines, and at first I thought you might be right, because one of the sites is a Windstream fiber circuit that has Dynamic IP lines (SIP-to-POTS), but the other sites have the same problem, and they are other carriers.

I know the carrier is placing the call, because if I dial 9,611 I get the first 5 seconds of the message, then it goes rapid busy. I am almost positive this rapid busy tone is coming from the SV8100 because its the same exact rapid busy tone I hear if I dial say 9,7 and wait 5 seconds.
If I go to 21-01-03 "External Call Inter-digit Time" and change it from the default of 5 to say 10, then I dont hear the rapid busy until after 10 seconds. If I set it to say 30, I can call 9,611 and hear the first 30 seconds of the message, then the SV8100 gives me the rapid busy.

Do I need to enable ARS to set the max digits?

 

[belevedere]

Max digits is only available with ARS. This may be your only solution.

 

[OzzieGeorge]

Seems to me that if this isn't in the NEC system (you say NEC can't find the problem) then it is the Carrier that isn't signalling the connection of the call and the system is effectively saying "I can't connect you" I would be looking to the carrier or the equipment that is acting as carrier.

 

[FortKnox]

I finally figured out the problem.
I had incorrectly added @@@5551212 in the wrong area in an effort to keep employees from calling AREA-CODE+555-1212.
When I did this, the system still allowed 7 and 10 digit dialing, but not 3 digit dialing.

 

[RlsMe]

So where did you end up adding @@@5551212? Because I would like to add that as well as @@@976 into my restricted tables but can not get it to work without messing up ARS in general (911 included).