A friend recently asked me how many email addresses I had; her family thought she was a geek because she had six. I guess I’m a little more geeky: I have over one hundred eighty email addresses. Every time a company asks me for an email address, I generate a new one just for that company and arrange for incoming mail to show up in my normal inbox (I’ve automated this to a single command line in Linux). If the company abuses my email address by sending me spam, I disable the email address. Disposable email addresses guard my privacy.

I’d certainly like the same system for telephone numbers, because sometimes a company will get hold of my phone number and never let go. (Horror stories deleted; fill in your own.) Internet Telephony provides a solution. One reason Internet Telephony is a revolutionary innovation is that IT takes the ability to establish telephone numbers away from a central authority and gives it into the hands of anyone who wants to terminate calls. Telephone numbers become an unlimited commodity instead of a precious — and lucrative — resource.

Until IT becomes ubiquitous and all telephones can dial using the “sip:foo123@example.com” syntax, I’ve devised an alternative scheme to achieve disposable telephone numbers: use a single telephone line, but assign each company its own extension.

I’ve written a demo Disposable Phone Numbers application in CCXML, VoiceXML, and Java, running on Voxeo’s free Prophecy server. As each call comes in, the caller is asked for an extension number, which the caller provides using spoken words or touch tones. The extension goes to local Java servlet, which does a check of the extension number (it should be a database lookup, but my prototype just checks against a short internal list). If the extension is valid, the call goes through; if the extension is invalid, the application drops the call. If anyone is interested in hearing the pre-alpha — and the user interface is just barely good enough at the moment — they can try it by calling the demo number at +1 312 957 6568, which terminates at a computer on my desktop. At the moment, the only two valid extensions are 3350 and 8932, and all calls are dropped. If there’s enough interest I’ll release the application as open source.