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Managing Editor

Old-school VoIP

Jan 23, 20065 mins

Collectors hook up legacy phone gear with modern packet equipment.

What began as a conversation on the TCI mailing list in the fall of 2004 culminated a few months later in the Collectors’ Network, a working VoIP system linking TCI members that uses the old gear stored in their basements, barns and garages.

Dennis Hock, a collector of antiquated telephony gear, wanted to make the treasures in his home ring. He figured that would require a manual switchboard, however, and his wife wasn’t keen on helping out by playing operator.

“You start collecting phones, those are cool,” says Hock, whose day job is network engineer at DTE Energy in Detroit. “Then you display them. The next logical step is that you’d like to be able to see them work.”

As it turns out, fellow members of the Telephone Collectors International (TCI) were having similar thoughts, and the result might actually help demystify one of the big issues surrounding VoIP: how to make new packet-based systems work with old – in this case, really old – circuit-switched gear.

What began as a conversation on the TCI mailing list in the fall of 2004 culminated a few months later in the Collectors’ Network (CNET), a working VoIP system linking TCI members that uses the old gear stored in their basements, barns and garages. Hock refers to collectors like himself as the “weirder” ones, in that they fancy electromechanical switches built in the 1930s that can be 8 feet tall and weigh as much as 700 pounds.

The collectors chose the Internet as their medium to connect these old switches and phones into CNET. Tariffed public switched telephone network (PSTN) circuits served as tie lines, and trunks were priced by the mile, making them prohibitively expensive.

We “started discussing the possibility of doing it through VoIP. It really took off from there,” says Greg Blakely, a collector and one of the creators and administrators of CNET. He and some other collectors, dubbed switchers, had been monkeying around with Asterisk open source VoIP PBXs out of curiosity and deployed them as tandems to the restored electromechanical switches.

A central switching scheme was established, office codes were assigned and an automated method of looking up call routing was put in place. CNET was born.

The network connects 17 members – 14 in North America, two in the Netherlands and one in the United Kingdom. In addition to the Asterisk PBXs, the network equipment includes cord switchboards; cordless switchboards; key telephone units; and step-by-step, crossbar and panel switches.

There are two ways to connect to CNET: One involves an onsite Asterisk PBX on the originating end; the other involves an analog telephone adapter (ATA) on the originating end. In the CNET setup, the ATA serves as the dialing intermediary between the originating end and the Asterisk PBX.

How’s the quality? Blakely says the problem isn’t with the old equipment itself but with the Internet – especially if his kids are playing games online.

“Because my upstream ISP doesn’t pay attention to the tagging I put on my packets, everything is treated equally and I sometimes get some dropped packets,” he says. “Every router along the way [on the Internet] has to have QoS. You also have to hope there’s no congestion issues in the middle.”

For on-net CNET calls, Blakely says he has implemented a “poor man’s version” of QoS with a Linux firewall called IPCop.

“I have it set to where [TCP and UDP] Ports 45, 69 and 50-60 are the highest precedence and everything else is very low precedence,” he says.

Anyone can connect to CNET; you don’t need to be a telecom professional or have a family heritage in telecom, as Hock and Blakely do. (Hock’s father worked at the old Michigan Bell for 25 years.)

All you need is a high-speed broadband Internet connection and some adapters and converters, rather than an onsite Asterisk box.

“There are codecs available that are supposed to be good enough to where you can do it through dial-up,” Blakely says. “But it really sounds pretty crummy, and we haven’t really had much success – there are latency issues and voice-quality issues that hadn’t worked out for the one guy that tried it.”

That one guy is a switcher in Lancaster, Pa., who can’t get broadband Internet service.

“He’s got everything working and ready to go, but all he can get is dial-up and his voice quality is very poor,” says John Novack, a semi-retired telecom consultant who helped create CNET. “They need a little more bandwidth than the 50Kbps you can get on dial-up. Much less than 128Kbps, you can’t do much.”

Another limitation is the Asterisk box, he says, adding that the product’s ability to interface with legacy loop and transmit-and-receive E&M lines is weak.

“That’s kind of unfortunate,” he says. “I don’t know if that’s going to evolve. . . . [But they’re] going to have to because the PSTN is going to be around for a while.”

Novack and other TCI members will make sure that the old telephony equipment stays around for a while. Now that it can be interconnected via VoIP, might that change Hock’s wife’s mind about participating in his hobby?

“No,” Hock says. “She tolerates it. But she doesn’t understand the need for all of this equipment.”

Managing Editor

Jim Duffy has been covering technology for over 28 years, 23 at Network World. He covers enterprise networking infrastructure, including routers and switches. He also writes The Cisco Connection blog and can be reached on Twitter @Jim_Duffy and at

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