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Do-It-Yourself VOIP Telco
DamnYankee writes "Robert X. Cringley predicts the coming demise of the landline telco monopolies from the grassroots encroachment of VoIP and Linux on the latest generation of Wifi routers. According to Bob, 'The result is a system with economics with which a traditional local phone company simply can't compete'. With Linux capabilities and builtin VoIP any Mom and Pop can become the local equivalent of a cellular phone company for the price of $79 Wifi router. Now how is Verizon going to compete with that? Get the full scoop from the man himself."
Hm. This is new information for me. I thought a vox T-1 was muxed at the packet level. Now you're telling me that it's muxed in some other way?
Yup. The term you're looking for is "Time Domain Multiplexing" - TDM. Each channel gets a time slice of the circuit, just under 1/24th of the total. There's a bit of overhead. This 1/24th, or 64k is allocated *whether that channel is in use or not*. And while it's in use, the "user" gets all 64k of it. Even if the mouthpiece of the phone is disconnected and nobody's talking the other way - no use on the 'line' whatsoever - the call is still using the 64k channel.
Cell or packet switching is a different animal altogether. A given channel may have a certain bandwidth guaranteed, and may be able to use well over that guaranteed amount, depending on the technology and lots of other stuff. Your average cell/packet circuit is only firing cells about 10% of the time.
The TDM part of a data circuit puts a hard limit the overall bandwidth. If you've got a T1 connection to your ISP, you can't send/receive more than 1.544Mbps, even if the ISP's router can switch hundreds of Mbps and they have an OC12 to their next peer. And if the site you're communicating with depends on an even lower bandwidth connection - such as when a dial-up user hits your ftp server - then *their* circuit is the limiting factor.