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Showing content with the highest reputation on 01/11/2018 in all areas

  1. 6 points
    Here's the complete collection of recordings I grabbed of the Odessa 1AESS switch before the cutover. The recordings were made during late may, with the last batch (A-D recordings) made on June 2, 2017 -- days before the cutover. The most interesting recordings I found during the calls to the switch: 1AESS-A.wav - Highest quality recording/best example I have of what a normal call to the 1AESS intercept sounded like. Allows you to hear the background SIT-tone noise before recordings. 1AESS-D.wav - Highest quality recording/best example I have of what a normal call to the 1AESS supervision test sounded like. 1AESS-3.wav - Bizarre because the switch cut to busy after intercept, instead of cutting over to reorder like normal. 1AESS-11.wav - Bizarre because the call, without ring, goes to the 1AESS intercept recording for one cycle, then stops for 20 seconds, and returns the Hillsboro 4ESS '121-T!' recording. 1AESS-14.wav - Bizarre because the call, rings once, goes silent for 30 seconds, then returns the Hillsboro 4ESS '121-T!' recording. 1AESS-15.wav - Bizarre because the call, rings once, goes silent for 40 seconds, then returns a reorder. More descriptions on the other calls are available on the 1A_desc.txt file on the dropbox drive. https://www.dropbox.com/sh/xca3wwskn1mzwzt/AABJMpTS0XDL9NQQgiz4LVI4a?dl=0 Enjoy.
  2. 2 points
    I go all over the US for work and vacation, and when I do I like to see how the local network homes on various tandems (AT&T, MCI, Sprint) when I can. I like to do it from landlines and cellphones since both route differently. I also do this with VOIP carriers since often times they dump you on the POTS network at various places, and this can either be static or dynamic. (Can you say Tandem round robin?) Often times calls from landline, cellular or VOIP go to the newer "edge switches" that are in the format of NPA-xL (like 412-9L). I believe most of these are 5ESS based. But most of the time you can reach a 4ESS in the format of xxx-T. Anyhow, I was in a very rural place in Wyoming in May while on vacation. It was a rest stop in the middle of nowhere. The rest stop used to have a pay phone (you can tell it was there and removed), but they did have a microcell for Verizon Wireless (obviously fed by DSL). Doing my test for AT&T, it did the round robin as I suspected (some sort of VOIP backhaul) and I came up on 088-T a few times. That *used* to be the AT&T tandem for San Diego. They retired the 4ESS a few years ago, but now it comes up in the "new" voice that AT&T is using for the new generation "N4E" system.The N4E uses the old 4ESS software hosted in a virtual environment in newer hardware (lot smaller footprint and more in tune with modern packet switching). Sure enough, I was in San Diego last week and tried it from a COCOT. Yup, they do have a new N4E and has the new voice on the trailer. So I'm wondering how many of the existing 4ESS systems will be replaced by N4E systems? I also wonder how many 4ESS and N4E systems are out there. I found a N4E in Scottsdale, AZ (NPA 480) not too long ago. Haven't explored what else is new out there recently.
  3. 2 points
    I picked this up in a heap of old computer, radio, and telephone equipment, from a guy who had been an engineer in the Navy, then an engineer/lineman/programmer at Bell Labs in NJ: It's an *actual* milliwatt! I can't find the BSP for it online, but I did find a hardcopy on eBay, so I'll scan that in when I get it. Battery test points, this is the battery (well, the top of an old one): 45V "B batteries" were common in old radios and other higher-than-we're-used-to voltages were common in other types of test gear. For instance, a kick meter uses a different 45V battery (looks like a giant 9V and is still made). Top of the internal circuit subassembly, the battery goes in the space seen at the top of the picture: Here's the circuit: Typical Western Electric, potted networks, switchboard jacks, and expensive resistors and capacitors. Not yet sure if the pot varies pitch or level. You can see there's a single very old GE transistor in a metal can package clipped to the side of the uppermost (4002A) network, presumably the only active component in the circuit.
  4. 1 point
    From what I heard several years ago, the later 4ESS switches that were installed in the mid to late 90s were of a newer generation than those from 1976 to the late 80s. And yes, some of these switches are 40 years old!! But as TP said, over time I bet most of the guts have been replaced (though I do wonder about the announcement machines - some of which are quite broken!). But I think to say relevant, AT&T like a lot of other telcos are going VoIP. I know Verizon basically runs it's old school POTS TDM network and a VoIP network in parallel with gateways to cross connect the two worlds as necessary. Yeah, AT&T has introduced DMS-250, 5ESS, etc. into the long distance network, but the venerable 4ESS is still the backbone. Just curious what their strategy is to play in a mixed TDM and IP environment moving forward.
  5. 1 point
    037T was just converted from old 4E to N4E dialed from Indonesia. 038T as of a few days ago has not been converted. Both of those tandems are located in Houston, TX, where I live. 037T.flac