Windows Mobile 2003/iPAQ h6315

The following question was submitted to editors. Can you help? --------------------------------- Our senior executives are each equipped with an iPAQ h6315. We all travel overseas, and would like to be able to secure our voice conversations. How can we encrypt voice on a Windows Mobile device like the h6315, both at the h6315 and at the other US-based PSTN/POTS ends? -- Ian D. --------------------------------- Kara Gattine, Associate Editor and

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The question doesn’t say which countries are visited, so I’ll start with the assumption that most of the overseas systems visite by this inquirer are GSM systems.
1)The first thing to note is that GSM systems are inherently well encrypted. As long as the phone is in digital mode, and not operating on an older, analog system, the call is essentially secure from all but phone company and government eavesdroppers. The same is true for the other digital technologies, but if you’re roaming on an analog system, you’re not secure at all.
2) Inter-system traffic is often converted to various standardized formats: analog, T1, E1, J1, etc. This means that, even though the call is safe from casual eavesdropping at the air interface, it’s still subject to monitoring within the telco carrier’s system.
3) If espionage, either corporate or governmental, is a real concern, then the real cure is one of voice technology’s oldest: an analog scrambler. These devices, which date back to at least WWII, garble the audio before it’s ever placed on the phone line. It isn’t part of the phone system, you have to carry it with you, and it would be difficult to interface with the microphone input of a modern cell phone.
–Bob Young

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  • SearchNetworkingEditorialTeam
    Hi Bob, thanks again for your insightful response. I sent an e-mail to Ian and he had this to say (Maybe he'll see the value of this forum and become a member ;-) We are travelling all over the world, and find mostly GSM networks. We would like our conversations to be secure while traversing foreign telcos, so from a 6315 to a POTS handset in our offices would be ideal, less so might be 6315 in the field to a 6315 in the office. The external analog scramber might work, except we're talking executives here, none of whom are likely to carry one, especially me. Encrypting the conversation inside the PDA is the goal, so that it's encrypted as soon as it hits the airwaves. That way, the only way to eavesdrop is with a shotgun mike pointed at the person talking, and intercepting the cell call anywhere in its path is of no use. I'll keep watching to see if you have any further comments or if someone else can jump in with their experiences. Kara
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  • BobYoung
    Kara, I can think of two other options: (1) For critical communications, use text messaging over a VPN connection, rather than voice. (2) If a voice conversation is essential to the speed and quantity of information to be exchanged, use IP telephony ? again, over a VPN connection. Below is a quote from an article about the h6315. ?The new phone does not come bundled with any voice-over-IP software, but a T-Mobile spokesman said that third-party VOIP clients such as Skype will run on it. Voice calls made over a wireless data network would not count against a user's allowance of voice minutes, the spokesman said.? (Source:,1895,1627202,00.asp) With regard to a VoIP solution, it should be noted that a private IP application, rather than Skype, can be installed and managed by the company. Any of the major US carriers that currently offer VoIP can provide a softphone application that works with their system. I see no reason why it couldn?t be installed on a Windows-based handheld PC platform (based on the information in the quote above), though I haven?t done it. The company that made the inquiry would also need to install a media gateway connected to the carrier?s system at their US office. Multiple US locations could be supported. I want to stress that this would only be secure if used with VPN encryption. --Bob Young
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