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March 2008 | Volume 11/ Number 3
Packet Voice Over Wireless

How do I call thee Let me count the ways…

There are now several ways to make international calls from your cell phone without paying typical absurdly high rates. They all use Internet VoIP for the long haul part of the call, but there are three main ways they get from your phone to the VoIP gateway: the 3G data channel, WiFi or the cellular voice channel.

For now the 3G data channel is marginal for VoIP performance, since the latency tends to be high, and in any case metered 3G data plans can limit your savings.

If you have a dual-mode (WiFi plus cellular) smartphone, you can put a client on the phone and make VoIP calls over the WiFi data network. SIP clients are available from numerous vendors, and some phones, like the Nokia Eseries and Nseries, even have a SIP client built-in. If you prefer Skype to SIP, Fring provides a thin client that connects back to a server which runs the Skype protocol. Not all dual-mode phones support these options; Windows Mobile and Symbian 60 phones are among the most compatible.


But dual-mode phones are relatively rare, and WiFi access is intermittent. More universal are the VoIP-based services that use the regular cellular voice connection to get to a local number, then route the international call over the Internet. There are many such services that you can use by dialing an access number, but dialing is a hassle. If your smartphone supports it, you can download an application that removes the pain by invisibly using the access number whenever you make an international call. This appears to be how MobileTalk and MyGlobalTalk work.

Several services convert the access number requirement from a nuisance into a feature in an ingenious way that doesn’t require a smartphone or software download. For example, you tell Rebtel which international numbers you dial frequently, and Rebtel associates a local access number with each one. When your cell phone’s caller ID lands on that access number, Rebtel knows to connect it to the associated international number. So for each of your international contacts you simply program a local number into your dialing directory.

Jangl and Jaxtr work in a similar way, but with a social networking twist. You have a ‘call me’ icon which you put on your emails and web pages. When somebody clicks on it, the service requests their phone number, then dials both parties and connects them. Each party captures the caller ID of their local gateway, and can use it to call each other back later. Neither party needs to give out their real phone number to web contacts. IT

Michael Stanford has been an entrepreneur and strategist in Voice-over-IP for over a decade.

» Internet Telephony Magazine Table of Contents



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