tro@uunet.uu.net (Tom Olin) (09/24/90)
Please pardon my ignorance. I don't work in the telecom industry and I don't know many of the technical details. Several contributors to c.d.t. have discussed the method of transmission of data calls vs voice calls over the network. They have pointed out the higher bandwidth utilized by data calls and the problems of multiplexing such calls. I would like to better understand the nature of this multiplexing. Suppose that we have enough simultaneous voice calls to saturate the capacity of some portion of the network. As the other writers have mentioned, these voice calls are assumed to have a duty cycle of less than 100% - let's say 50%. What happens if all those callers simultaneously break into song or in some other way push their duty cycles up to 100%? Do they start losing parts of their conversations? Or do pieces merely get delayed? Or does something else happen? Tom Olin ...!uunet!adiron!tro (315) 738-0600, Ext 638 PAR Technology Corp, 220 Seneca Tpke, New Hartford NY 13413
tjo@its.bt.co.uk (Tim Oldham) (09/25/90)
In article <12542@accuvax.nwu.edu> adiron!tro@uunet.uu.net (Tom Olin) writes: >What happens if all those callers simultaneously break into song or in >some other way push their duty cycles up to 100%? Do they start >losing parts of their conversations? Or do pieces merely get delayed? >Or does something else happen? As another contributor has said, the technique of zero compression isn't prevalent on land nets. It is, I believe, prevalent on satellite links; certainly sometimes I get completely dead patches on a noisy phone line, which I have always contributed to zero compression. So, am I correct in this assumption? If I'm right, what happens when satellite virtual-circuits *do* start using more bandwidth. For example, Take a satellite which has 64Kbps bandwidth (it's a pretty crap satellite :-): time t: I'm on the line to the US from the UK, and it I'm on a zero-compressed satellite link. I'm put on hold, and keep my mouth shut. No bandwidth being used. time t+1: Another person decides to call the US. Whatever-it-is decides that statistically (assuming a 50% zero compression winnitude), and currently actually, there is sufficient bandwidth to route the call via the satellite. It does so, and the 2 parties are connected. They start talking. No problem; plenty of bandwidth, as I'm still not saying anything. time t+2: All four parties start screaming blue murder at each other. We need 128Kbps bandwidth. Which the satellite can't deliver. What happens? Is it just a case of the designers allowing for statistically very low data loss, given that the numbers are very much bigger for a typical satellite? If not, what techniques are used? Yeah, I work for a telecomms company, but I'm not directly involved in telecomms. Just interested. Tim Oldham, BT Applied Systems. tjo@its.bt.co.uk or ...uunet!ukc!its!tjo Living in interesting times.
JDurand@cup.portal.com (09/26/90)
In Message-ID: <12542@accuvax.nwu.edu> adiron!tro@uunet.uu.net (Tom Olin) writes: >Please pardon my ignorance. I don't work in the telecom industry and >I don't know many of the technical details. I work in the industry and still don't know a lot of the details. 8-) >They have pointed out the higher bandwidth utilized by data calls >and the problems of multiplexing such calls. >What happens if all those callers simultaneously break into song or in >some other way push their duty cycles up to 100%? It just occurred to me that all of us people sitting on hold all day should have the lowest duty cycle except for the constant music-on-hold that raises our duty cycle up to that of the dreaded modems. Does that mean there should be higher rates for companies that put people on hold for a large percentage of their calls? 8-) Jerry Durand, Durand Interstellar, Inc., jdurand@cup.portal.com, 408 356-3886
vances@xenitec.on.ca (Vance Shipley) (09/28/90)
In article <12624@accuvax.nwu.edu> tjo@its.bt.co.uk (Tim Oldham) writes: >links; certainly sometimes I get completely dead patches on a noisy >phone line, which I have always contributed to zero compression. >So, am I correct in this assumption? If I'm right, what happens when I doubt it. I would bet it was a case of squelch. when the talking stops they suppress the background noise. It's meant to help but many find it disconcerting. The Toshiba Strata key systems used to do this (some) on CO calls. People would hang up thinking they'd been disconnected! vance
ashbya@uunet.uu.net (Adam J. Ashby) (09/28/90)
In <12630@accuvax.nwu.edu> JDurand@cup.portal.com writes: >In Message-ID: <12542@accuvax.nwu.edu> adiron!tro@uunet.uu.net (Tom >Olin) writes: >>What happens if all those callers simultaneously break into song or in >>some other way push their duty cycles up to 100%? >It just occurred to me that all of us people sitting on hold all day >should have the lowest duty cycle except for the constant >music-on-hold that raises our duty cycle up to that of the dreaded >modems. Does that mean there should be higher rates for companies >that put people on hold for a large percentage of their calls? 8-) >Jerry Durand, Durand Interstellar, Inc., jdurand@cup.portal.com, 408 356-3886 Not necessarily, BUT there should be a HUGE, financially crippling charge for those companies that employ the usual muzak-on-hold, even if they don't keep people on hold that often or for that long. 10 seconds of the usual dross is enough to make me hang up. Adam Ashby | Most, if not all of the above (+1)(708) 632 3876 - work time | came from my mind...and not (+1)(708) 934 1431 - play time | even I have control over ...!uunet!motcid!ashbya | that. - madA 1990