Best Enterprise VoIP client for the iPhone? Don’t bother….
by Craik Pyke on 10/11/09 at 3:32 pm
Craik Pyke is telecommunications architect and software developer specializing in mobile applications and an editor for iPhoneCTO.
In all the publicity over GoogleVoice (which is not VoIP by the way), the iPhone’s ability to perform VoIP on WiFi networks tends to get marginalized. As an iPhone user within an enterprise though, I was quite excited for the potential to have my office phone with me whenever I’m in an area with WiFi. To that end, I decided to preview a number of VoIP (SIP specifically) clients to see how well they work work with a SIP PBX, with the goal of having my work number available on my iPhone.
As the investigative process proceeded, I kept coming back to one fundamental conclusion that overshadowed the VoIP clients themselves… More on that later.
Finding SIP-VoIP applications in the AppStore was not difficult. I decided on five applications that permitted configuration to any SIP server. The five applications I selected were:
- Acrobits Softphone by Acrobits

- iPico SIP Client by MailVision Ltd.

- iSip with Push Service by Shanghai KaiWei Network Technology

- Media5-fone by Media5 Corporation

- WeePhone SIP by Justin Brady

My goals were quite simple; test each client using the two SIP servers I had available to me (an Asterisk server, and a SIP server from a large telecom provider). Since the accounts I was using are corporate accounts, I was not willing to use any service that required me to put my credentials on an untrusted server for push notifications or other purposes. I realize this seems like a pedantic concern, but I wasn’t willing to expose the credentials to a corporate server beyond placing them in the client itself.
The featureset I was testing was as follows:
- Could I make and receive calls such they they appeared to come from my corporate number?
- Could I transfer calls to other internal corporate numbers?
- Could I create an ad-hoc 3-way call?
- Was I notified of voicemail and could I retrieve voicemail?
- Was the Voice quality tolerable?
Acrobits
The Acrobits client could not register with my primary corporate server. I could give it a pass for not being able to deal with the “big telecom” system, but sadly I couldn’t even get it to register with the Asterisk server despite mimicking the settings I use for other SIP clients.
iPico
I fared better with the iPico client. I was able to register it with both systems and I could make and receive calls. I did encounter one problem with receiving calls. The “big telecom” system allows multiple calls to be sent to a client. For example, if I’m talking to Bill and Yves calls, the SIP server sends both calls to the client so the user can put one call on hold and answer the other. When this occurred with the iPico client, the client actually dropped both calls rather ungracefully. The iPico client did not have the ability to transfer calls or to create a 3-way call and it didn’t have voicemail notifications. Voice Quality was quite good and the latency was fairly low.
iSip
In my opinion, the iSip client was the best of the bunch. The UI was clean, it was easy to configure and it fared the best in my tests. I was able to register it with both systems and make and receive calls. Additionally, the iSip client supports transferring calls to other numbers, though it didn’t have the ability to create a 3-way call and voicemail notifications seemed to be incompatible with the “big telecom” server. Voice quality from a subjective perspective was quite good, although a bit quiet. The latency was a little bit more detectable than with iPico, but still good.
Media5
Media5-fone is also a very good client. It was easy to configure and the home screen is reminiscent of the iPhone’s dialer. Despite also not being able to display voicemail notifications, Media5-fone did have a voicemail access button that made it easier to retrieve them. Media5-fone doesn’t offer transfer or 3-way calling features. In terms of voice quality, the latency was the lowest (the best) of all the clients. On the downside, the volume was so loud as to be slightly problematic. Also, Media5-fone is the only client that didn’t offer account settings while in the application – instead you have to use the iPhone Settings panel and modify accounts settings from there.
WeePhone
WeePhone was actually the first of the clients I tested. At first, I was unable to get it to register to the “big telecom” server. The designer responded to my support request within 24 hours and provided me with a new version within a couple of hours after that. There is something about good customer support that elevates a piece of software in my mind. In terms of capabilities, WeePhone functioned well. As with Media5-fone, it doesn’t offer transfer or 3-way calling. It also offered no voicemail notification, but I could dial into my voicemail system and log in. There is a certain geek-factor to WeePhone in that it actually displays incoming SIP messages on the screen:
While I found it interesting to know what was going on, I’m not sure everyone would be so interested. WeePhone also informed me of missed calls once my active call was over. Voice quality was very good and latency was low. The one significant complaint I have about the WeePhone interface is you need to manually clear the last dialed number from the screen before dialing another.
The Bottom Line:
With the exception of Acrobits, I would say any of the four clients are suitable for an enterprise user in conjunction with their PBX. I liked iSip best for meeting the majority of my requirements, but honestly it was a very narrow gap.
That brings me to the nagging fundamental conclusion I’d mentioned earlier… For all of the VoIP client: includng Skype, Fring, and NimBuzz, VoIP is fundamental broken on the iPhone! The iPhone makes all of these clients create their own dialer separate from the iPhone dialer. Additionally, the iPhone treats all data services as secondary to the cellular voice services (in wireless terms, packet connections are secondary to circuit connections). Imagine you’re in a WiFi hotspot and you’re using a SIP client to call through your company’s PBX. You are speaking to a client about an urgent issue and then your wife calls your cellular number to remind you to pick up milk. The iPhone will close the data connection and switch to the iPhone dialer so you can handle the voice call. Your data session (your VoIP call with that client) is gone.
I know what you’re thinking; the need for true background processing for the iPhone has shown itself again, right… No. If the VoIP app is backgrounded and at best the call is put on hold, you still have to fumble around, ignore the cellular voice call, switch back to the application, and take the call off Hold.
The requirement for good VoIP applications on the iPhone (SIP, Skype, even GoogleVoice) is that Apple must allow applications to integrate with the iPhone dialer. When that happens, then the iPhone can understand and handle the fact that you’re on a (VoIP) call when another (cellular) call is received.
While there are some good SIP clients available for business users, it’s probably not worth the money and frustration you’ll inflict on your workforce. If Apple does the right thing and properly supports 3rd party VoIP applications, we’ll talk about this again.

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