Monthly Archives: April 2010

Use Asterisk to give your cell phone a break while travelling.

If you travel frequently, you’ll often find yourself in an airport, hotel, or eatery that offers wi-fi access. Combined a few other technologies, you’ll be able to use that wi-fi to make and receive phone calls using your company’s phone system rather than your cell. You’ll save cell minutes and your battery, plus have access to the power and flexibility of the company PBX. Here’s what you’ll need:

  1. Asterisk-based VoIP business phone system (PBX)
  2. softphone, such as CounterPath’s eyeBeam installed on your notebook.
  3. Bluetooth headset (the same type used with most cell phones)
  4. and optionally, VPN software, such as the open-source OpenVPN.

Asterisk

If you’re reading this post, you’re probably already familiar with Asterisk. But if not: Asterisk is an extremely popular, open source PBX application that runs atop of a Linux-based server. It can be configured to use your business’s existing phone lines and phone numbers, and replaces the phone system that is likely hanging on the wall in your telcom closet. RightBrain Networks is a Michigan-based an Asterisk integrator and can assist you any additional questions you have about about the system.

Softphone

The softphone is a computer application that simply mimics a physical office phone. CounterPath’s basic eyeBeam product is less than $34 per copy and is well worth the money. However, if you’d like to test this setup or would just like to save a few bucks, you can also use their free softphone, X-Lite. Once you’ve downloaded and installed the softphone, it will have to be configured to talk to your Asterisk server. You will need to know your SIP username and password, as well as the hostname of your Asterisk server. The person or organization that maintains your Asterisk server will be able to assist you with these steps.

Headset

In order to use your softphone, you’ll obviously need a microphone and speakers. You can use almost any type of mic that plugs into your computer. However, I’ve found that the most convenient choice is to use the Bluetooth headset that I’ve already purchased for use with my cell phone. This allows me to use the softphone exactly as I would my cell and doesn’t require that I be tethered to my computer. If your laptop didn’t come with an internal Bluetooth radio, you will need to purchase a USB Bluetooth dongle, such as IOGear’s GBU421 (under $20). Once your computer is configured to search for Bluetooth devices, associate the headset to the laptop and then check to ensure that it works with your softphone.

The VPN

The VPN portion of this solution is optional, but highly recommended. It will solve two problems: 1) There will be a firewall or similar gateway between the wifi connection you’re using and the Internet. Back at your office, your company likely has another firewall/gateway between Asterisk and the Internet. This double NAT configuration will cause issues between your softphone and Asterisk, with the most common problem being one-way audio. A VPN transparently zips through both firewalls, eliminating this NAT problem all together. 2) The packets of voice data transferred between your softphone and Asterisk (the RTP stream) are almost always unencrypted. Unfortunately, there are programs that can be found online that allow ill-intentioned people to snoop around and listen in on these unsecured conversations. However, everything piped through a VPN connection is automatically encrypted which greatly reduces the privacy concerns.

Enjoy!

In addition to saving cell minutes, I find that the most useful feature is that I’m able to make outgoing calls using the company’s CallerID information rather than my cell. It’s also nice to be able to easily transfer calls to between extensions or join conferences without having to dial in and enter a PIN. The one caveat though is that the connection quality is highly-dependent on how good the Internet connection is at the hotel/airport/restaurant. I would recommend that when you initially hook-up to a new wi-fi network that you place a couple of test calls to coworkers before taking calls from customers/vendors.

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