And so, you've been in the telecom business for years and you're hit with an unexpected problem - fast busys on your DID (Direct Inward Dial) Trunks.
Of course, you panic. Your T1 Spans are down?
But wait, the circuits to and within the PBX are running clean. And, strangely enough, calls are coming in on DID prefix 716.
However, external callers to employee extensions tied to the 718 prefix are getting fast busys.
You call Bell to report fast busys on the 718 prefix.
An hour later - a Frame Supervisor gets back to you to explain that there is nothing wrong with your inbound trunks.
Well, guess what - you're still getting fast busys on 718.
What is going on?
Answer:
When you moved to Direct Inward Dial - you probably ordered - let's say - 500 DID numbers, right?
You wanted them to be consecutive, right?
You ended up with two choices. Each choice contained a total of 250 consecutive DID's.
- 716 1000 thru 716 1249
- 718 3000 thru 718 3249
Now, your Bell Account Executive probably told you that the first choice was easy - the second, problematic.
Unfortunately the 718 prefix resides in the Choke Network. But, not to worry, any problems could be resolved in software.
Choke Network?
This is where Bell isolates entities that run contest lines.
Usually, Radio Stations. Check the Yellow Pages in your city and you will notice that the Radio Stations usually share the same prefix.
It's Bell's method of keeping the Public Switched Telephone Network free of fast busys when a Radio Station offers a pair of free Springsteen concert tickets or a promoter gives away a vacation of a lifetime to Tahiti.
Just imagine the speed-dialing city/state/countrywide. Without the Choke Network, Traffic Engineers would have to start thumping their calculators at the speed of light.
So, be aware. Whenever you are after consecutive DID's - be sure to ask if the numbers reside in a Choke Network.
Who cares, right? No big deal, right? So what? Hey, I had to have the consecutive numbers and besides - I'm covered by the software.
What can go wrong?
Well, what if the Central Office Switch goes down and has to be physically rebooted? Patch City can create havoc with traffic routing. What if a programmer reverses a couple of digits? You're in the Choke and maybe out of business.
If you want to get a handle on anything in telecom, be sure it is inbound trunking. It's the lifeblood of any business.
Don't get caught in the Choke.
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