HEISON CHAK voice over IP with Asterisk Heison Chak is a system and network administrator at SOMA … include => real_extensions [real_extensions] exten => 100,1,AGI,wakeup.agi exten => 101 … He focuses on network manage- mentand performance analysis of data and voice networks. Heison has been an active member of the Asterisk community since 2003 and will be delivering a tutorial on VoIP Principles and Practice atthe USENIX ’05 Annual Technical Conference. heison@chak.ca ASTERISK IS A SOFTWARE-BASED PBX that runs under Linux, *BSDs, …

Wake-Up Calls Beforegoing to bed, I dial ext. 100 from any phone in the house to request a wake-up call, and the voice of Allison Smith (Allison is the voice of Asterisk) prompts me for the desired time. At 6:30 a.m. that morning, Asterisk called the auto-answer extension of my IP phone in the bedroom. Besides telling me that it was a wake-up call and announcing the current weather in Toronto, Allison also challenged me to repeat a four-digit number after her. If I failed to respond or if I hung up after three tries, Asterisk would call for help, playing back my own recorded voice begging her to wake me up on that same auto- answer extension. The last resortwould usually get me the unpleasant voice of my mother. Dynamic Contents That morning, I managed to get out of bed before Asterisk escalated the call, yet I missed the weather report when Allison did the announcement. I wanted to double-check the weather in both Toronto and San Francisco, as well as make sure my flight was on time before heading out to the airport, but my laptop was already packed away. With the help of a PHP script on my Web server, I was able to look at reformatted contents from theweathernetwork.com and aircanada.com on my IP phone as I hit the service button. Calling ext. 102 invoked weather.agi, allowing me to get a more detailed weather report based on the three-digit airport code (e.g., 736 for SFO and 999 for YYZ). A TTS (Text-to-Speech) engine from Cepstral was used to announce the weather forecast of the requested city. After hearing that Toronto’s temperature was in the minus 40s, I was happy to find out San Francisco would be in the mid-60s throughout the week. IAXy Given it was a Monday morning, the check-in line-up wasn’t so bad. However, I was not making friends with airport security, especially when they found this little blue thingie in my luggage and wanted me to explain what it was: “Okay, this blue thingie is called IAXy (pronounced ‘eek-see’); it’s an analog telephone adapter that allows telephone calls to be made over the Internet with a regular telephone, and the ‘y’ in IAXy doesn’t stand for anything, it’s just a product from Digium ( http://www.digium.com ) with a cool name.” Then, I heard a very familiar voice saying, “Yeah, this is similar to what Vonage and other voice-over-broadband providers are offering, but he is doing it with some open source software.” I turned around and there was my boss, who was traveling with me. I was glad he was there, or there would have been a good chance I’d have missed my flight. Toll-Free Service Ipromised to call home when I landed, but my cell phone had very poor reception at the baggage claim. So I went to a pay phone and dialed my home number without inserting any money…

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