Use your cell phone as a WiFi VOIP phone

The phone in your pocket might be your best office phone

Does your home or office use a VOIP based phone system? Wouldn’t it be great if you could use your cell phone as a VOIP phone instead of running back and forth to your desk whenever the phone rings? It turns out that this can be a reality quite easily, provided you can wrangle the proper details from your IT folks.

In our office we run an Asterisk PBX system which has served us well for years. The system is simply a linux server connected to our network which manages our phone calls internally and communicates with a VOIP provider to connect to the outside world. On our desks we have SIP phones which register with that server and act just like a normal telephone only they’re connected via Ethernet and have an IP address.

Recently we ran out of SIP phones as two bricked on us. We messed around with a few PC based softphones which worked, but the result was less than ideal, especially since you had to either take your call on speakerphone or throw a headset on every time. While we were working through these issues it dawned on us that it would be amazing if we could just use our normal cell phones as a SIP phone if we wanted. It turned out that everything we desired was just an app away, a free app at that.

On Android we downloaded the app CSipSimple. This gem handles VOIP calls perfectly for us, and the best part is that it’s completely distinguishable from normal phone calls. When an incoming call comes in via VOIP, a distinct answering screen appears that is similar to the normal dialer but different enough that you know it’s a VOIP call and not a cell call.


You also get a dialer that is very similar to stock Android but is launched by it’s own icon so you always know which type of call you’re going to make.


Setup is flexible and there should be a proper fit for any need. In our case we used the Basic Setup and configured the device to only be available on our local WiFi which is awesome. When the device enters the door it picks up our WiFi and automatically registers itself with our PBX system and becomes available. When the device leaves the premises it is no longer registered on our network and calls to that number go to voice mail. That way you won’t get work calls on your cell when you’re home on the weekend.

You can also set up the device to work over cell data as well. This allows the cell phone to act as a desk phone no matter where you are which, for some, is a huge benefit. Caveats for this configuration are that your PBX needs to be WAN accessible and you need to consider cell phone data restrictions and charges.

You get all of the features you’d expect from a SIP phone, caller ID, transfer commands, etc. along with added benefits like video calls. It’s the perfect solution for someone in need of an office phone but doesn’t want a desk phone or doesn’t get enough calls to justify one.

On the iPhone there is an app called Zoiper which is also free and provides equally good functionality. The Zoiper app is available for Android as well so it is a good option for standardizing the software users are installing.

So unchain yourself from your desk and get your pace on while you work.

Read more of Matthew Mombrea's ByteStream blog and follow Matt on Twitter (@mombrea) and Google+. For the latest IT news, analysis and how-tos, follow ITworld on Twitter and Facebook.

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