Cisco's latest tag line is "This is the power of the network. now." A little $210 box released in 2001 illustrates one instance of Cisco's power.

by Alex Goldman ISP-Planet Associate Editor [November 14, 2003]

When the package from Vonage arrived on my colleague's desk, I wanted to look inside. He opened the package to reveal little more than software, documentation, and a key piece of hardware: a Cisco ATA 186.

The device is called an Analog Telephone Adapter because it translates digital data into analog information for your telephone. Conversely, it translates the analog output of a conventional telephone into data that can be transmitted over digital connections. Further details are available on Cisco's website, referenced above.

In the latest generation of supposed killer ISP services, from wireless broadband to VoIP, the difficult element in the cost equation is the Customer Premise Equipment (CPE). The ATA lists for about $210, and is not a new product. In fact, it was released on May 21, 2001.

I had been expecting technology I had not seen before, but on reflection, was thrilled to see something that was not too complex. VoIP seemed approachable and possible, perhaps even for small- and medium-sized ISPs. I decided to learn more, and called Cisco.

I spoke with Mark Bakies, Cisco's director of voice systems marketing, who has been using the product for some time.

Q: Have you used a Cisco ATA 186?

A: A lot of us at Cisco work more than 8 hours a day, and having an IP phone at home is great. We're an IP company. My experience with it is that 95 percent of the time it's a normal phone call. However, in most applications, VoIP is best used as a second line. There's a potential QoS issue, but, more importantly, it does not provide services like wiretap and 911.

Q: But doesn't Vonage offer 911?

A: Yes, Vonage has even begun to offer 911.

Q: What technology does the Cisco ATA use?

A: The ATA talks SIP. It also talks H.323. H.323 was based on H.320, which was invented for video conferencing. People saw that you could packetize just the audio stream. H.320 was an ITU stack. H.323 feels like BRI, like an ISDN stack.

Q: How does the server side work?

A: In SIP, the proxy server is the key element. The SIP protocol assumes that there are all kinds of intelligence levels in edge devices, from the basic ATA to some, like a UNIX server with 10 million lines of code, that can do a great deal. For example, the UNIX server can do voice mail, but the ATA cannot. A proxy can connect the ATA to a server that can handle voice mail. The proxy server can allow dumber devices to do advanced services.

Q: How do phone numbers work?

A: The address translation server does the directory. There's also a third SIP proxy type that can provide additional services like voice mail and three way calling. In order to provide its service, Vonage has to have operations systems, billing systems, subscribers in a database, and a lot more. Cisco makes the ATA, and we also make an address translation server, the Cisco SIP Proxy Server. They use other SIP components from other companies, and some stuff they built and wrote themselves.

Q: What happens when the ATA is connected to the Internet?

A: When your colleague gets the ATA, he connects it to a cable modem. The ATA was preprogrammed with a little information, such as where on the Internet is the Vonage SIP proxy (which IP address). So the ATA wakes up and it says, "I'm here on the network, what do you want me to do?" Then the proxy server configures it.

Q: Who uses the ATA?

A: It's not just Vonage. Other companies around the world use it too. Some use it as business termination, especially in the Asia-Pacific region. Sometimes it's easier to get data service than voice service. In nations where the infrastructure is evolving, computers may be more available than telephones. In some places in the US, it can cost $50 or $60 for a business landline. An SMB won't have a fat pipe for Internet access, and could use an ATA. A rural LEC could maintain the routing database. Note that the two-port version of the ATA allows you to prioritize voice packets over data packets.

Q: Could I have an ATA and use it to call directly to a branch office without going through a LEC?

A: You could put one in each office (but people tend not to). I would put in my ATA and tell it to connect to this one IP address every time—that would be the IP address of your ATA. You might have to do something to go through NAT, but you could do that. The difficult—and more interesting—application is to point the ATA to everyone. Then it gets more complicated. You have to know where's the hop off gateway for that call. Then the routing information is critical, and you may have to feed off to the PSTN through a voice gateway or a cable modem with voice jacks. People do this to some extent today. If your enterprise has a WAN, you can route calls over the WAN. It's called toll bypass, and it's not a hard problem. You want to use your WAN where you have the connectivity to save some money on long distance.

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