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chronomex

Tandem recording trailer codes

10 posts in this topic

When you call over a long-distance network and your call doesn't go through, you hear a recording from the last toll tandem in the line that handled it. Every carrier has their own naming scheme for tandems, but they almost always put the name at the end of the recording.

This thread would be a good place to post the tandem code, the CLLI of the switch it goes to (if you know it, otherwise just the area you're calling from), and the name of the long-distance carrier who owns it (or your outbound carrier).

I'll start.

132-A-11

WHPLNYWP08N

Verizon

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GR52T

RCMDVAGR52T

Verizon

A lot of Verizon's Southern intra-LATA tandems like to have recording IDs with the last five digits of the CLLI.

Not a bad idea, I like it.

503-2T

PTLDOR6203T

AT&T-LL

Nothing special, it's really 077T, one of the 4ESSes in AT&T's long distance network. They just gave it another

trailer code because...well, like, they're AT&T, they can do these things.

503-250

PTLDOR13C9T

Qwest

I'm not positive, but I'm pretty damn sure this is the ID that Qwest uses for the Portland access tandem. Like the

Verizon one, it handles a lot of intra-LATA functions, but it also lends a hand with feature group b/d stuff.

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I really feel like I should know this, but how do you identify the tandem that is playing a recording, and how can you access a recording on command? I've only heard tandem recordings while calling toll-free numbers, but that might just be because I have a shitty long distance plan so I don't scan LD. Do you run into them while calling long distance? So many questions...

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GR52T

RCMDVAGR52T

Verizon

A lot of Verizon's Southern intra-LATA tandems like to have recording IDs with the last five digits of the CLLI.

Not a bad idea, I like it.

I home on that tandem (DMS-200) for TOPS and AIS recording purposes.

Located in downtown Richmond Virginia. Building also houses a 5ESS and a DMS-100. At one time housed a 4A crossbar. The 4ESS for Richmond was built south of down in the 1970s (co-lo with a local Verizon 5ESS). (Picture on this page: http://www.co-buildings.com/midatl/804 )

I like the idea of tandem or LATA codes in the trailers. Helps you determine where you home for operator or LATA tandem services. :)

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You can get these a number of ways. Mostly by calling long distance (direct or through an operator/card services platform), but even sometimes dialing a local call can land you on a tandem depending on where you live and how your call routes.

The "132" in the first post happens to be a Verizon LATA tandem recording in NYC. (132 is the LATA for NYC). I've also heard "128" when reaching a Boston tandem (128 is the LATA code for eastern MA). Typical of the former NYNEX network (wonder what Fairpoint did with tandems in upper New England?)

AT&T's 4ESS tandems are in the form of xxx-T. MCI's DEX & DMS tandems are typically in the format of 2xx, and Sprint's DMS-250 tandems are in the format of xx-yyy where xx is the type of recording and yyy is the tandem code.

Qwest long distance (old LCI long distance) has their own trailers.. it's been so long since I used them that I've forgotten the structure).

LATA tandems are typically a "hub" of local incumbent LECs. In times past when it was all one network, local and long distance (AT&T LL) shared facilities. After deregulation, LATA tandems were installed to perform these functions at a local level and are only sent to AT&T's tandems for long distance purposes. Most of these LATA tandems are DMS-200 switches (a few are 5ESS). Right after divestiture, some of these were 4ESS local traffic tandems (Verizon in NYC had a number of these) but over time these were replaced with DMS-200 or 5ESS.

AT&T mostly uses the 4ESS (trailer code xxx-T) for long haul long distance, but the network has been added with "edge switches" which are primarily 5ESS switches that have a trailer code in the format of NPA-8L or NPA-9L (NPA of course is Numbering Plan Area, aka "area code"). I've heard both depending on a particular carrier routes calls, or how AT&T LL sets things up in a particular area. There are some areas that don't have any 4ESS switches at all and are all 5ESS.

Speaking of LD, Verizon Wireless tends to use their own internal network (not MCI, but I think one they created prior to them buying MCI) for LD, using AT&T or MCI where they haven't built their own network. T-Mobile uses AT&T (at least on the east coast), and of course at&t mobility uses AT&T (though a number of times your call gets trapped at the MTSO and doesn't even go to the 4ESS).

I have Verizon LD as my landline LD, and they have their own tandem trailer codes. I'm in former Hell Titanic territory, wonder how they do it in former GTE areas if they have their own network or if they just resell someone else's network (or use the former MCI network?).

So many questions... even for us who know the "system" :)

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074T

PHLAPAMPCM2

Verizon Wireless

That's an AT&T 4ESS tandem in Philly.

PHLAPASL42T

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I really feel like I should know this, but how do you identify the tandem that is playing a recording, and how can you access a recording on command? I've only heard tandem recordings while calling toll-free numbers, but that might just be because I have a shitty long distance plan so I don't scan LD. Do you run into them while calling long distance? So many questions...

This should help.

http://www.stromcarlson.com/misc/4ess.txt

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074T

PHLAPAMPCM2

Verizon Wireless

That's an AT&T 4ESS tandem in Philly.

PHLAPASL42T

Sorry about that.

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