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Phones Sound Different Worldwide
Tuesday, April 29, 2008
Image via WikipediaIf you've ever been to a foreign country and used a telephone, you'll know the phone just different--the moment you pick it up. Everything from the dial tone to the ring back tone to a busy signal and other things frequently sound different. Why? Custom, maybe.
What's interesting about this from a voice over IP perspective is where these tones are generated. On a typical landline, the central office generates all of these tones. You have no control over what those tones are on your handset.
In the case of an IP telephone or an analog terminal adapter, all of the tones you hear are generated on the device itself. The device knows, based on various telephony conditions, and how it's programmed, what tones it should play when.
The cool thing about this is that you can actually make an IP telephone or analog telephone adapter sound like any kind of landline you want. Let's say you're in Egypt and you have a voice over IP service there with analog terminal adapter. Depending on the device, it's possible to make that analog terminal adapter sound like a traditional Egyptian landline. Or, if you're a UK transplant into the States and you want your telephone to sound just like it does at home, you can do it.
Linksys devices allow complete control over all of the various tones that are played. Many other IP telephones and ATAs do not allow this kind of tinkering and may instead provide a simpler method for setting all the call progress tones to a specific country setting.
If you're trying to configure your Linksys ATA or IP phone, a good tool is the Linksys Localization Wizard at Voxilla, which I originally developed for them. Another useful site is World PSTN Tone Database at 3am Systems, which documents the tones used in many countries. It provides configuration information in both Sipura/Linksys format and Zaptel/Asterisk format.
