Thursday, November 19, 2009

Do You Need A Special Phone For VoIP?

I’ve been getting inquiries from people who are wondering if you need to buy a special phone to use VoIP as a replacement for regular telephone service. So, do you?

Answer: It depends.

Here’s why. You have probably figured out that you can’t just take a regular telephone and plug it into your router or broadband modem. The connectors aren’t the same size. That’s good, because you might just cause some equipment damage by plugging these incompatible devices together. What you need is a special phone designed to work on a data network or an adaptor for the phone you have now.

Most VoIP services designed for residential and home business (SOHO) take the adaptor approach. A good example is PhonePower’s VoIP service. You can get residential and small business plans with unlimited calling to the U.S. and Canada for $14.95 a month. Your order the service online and they send you a free adaptor for your phone. In this case it’s the Grandstream HandyTone 502 ATA or Analog Telephone Adaptor. You plug your phone in the phone jack that’s exactly the same size as the phone jack on your wall. You connect the ATA to your broadband modem or router using a standard Ethernet cable. Voila! You now have a regular telephone that works on VoIP.

But what’s going on in that ATA box to work the magic? There is circuitry that makes the phone connection look like it is coming right from your telephone company. That means generating the standard line voltage and ringing voltage that your phone is designed for. Those are analog signals because the phone is analog. The ATA also has to take care of converting between analog voice signals for the phone handset and digital packets for the Internet data network. This is done with CODECS or Coder/Decoders. In summary, the telephone needs to see its standardized analog signals and the Internet needs to see something that looks like a piece of computer equipment.

There’s a little more to it. Signaling for VOIP uses a standard called SIP or Session Initiation Protocol. SIP handles things like dialing and knowing when the phone is off-hook. SIP data is sent through the network just like other packets so it works just fine on the Internet or a private data network.

Because VoIP has become so popular for business, there are phones you can buy called SIP phones. These phones have the analog to digital circuitry of the ATA built-in. You can tell you have a SIP phone because it has a standard RJ-45 Ethernet jack on the back instead of the RJ-11 telephone jack. A SIP phone will connect directly to a LAN, a router or a broadband modem. It will need to be programmed for the VoIP service you are using. Some providers will give you instructions for how to do this. Others insist that you use their adaptor and an analog phone.

If you take your home phone into the corporate office, you may be shocked to find that there’s no place to plug it in. The company has installed an Enterprise VoIP system so that all desk phones plug into the corporate computer network. There is no separate phone network. All the phones are SIP phones. If for some reason you absolutely have to use your phone in that office, you’ll need to get an ATA and have it programmed to look like a SIP phone.

The bottom line is that regular telephones are analog. VoIP is digital. The way to make everything work is to use a phone that is matched to the network it is running on or use an adaptor to connect them.

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