iPhone video calling bandwidth burn rate and Video Relay Service (VRS)

*update 8/2/10* Installing My3G on a jailbroken iPhone4 now enables the use of FaceTime over the 3G network instead of WiFi.  The information in this post is now applicable.

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Kokonut Pundit’s post brings up valid concerns regarding using video relay service (VRS) over iPhone 4’s new video calling app called FaceTime.  When you have a cellphone that is capable of making video calls such as iPhone 4 or the Sprint EVO, the service comes with a monthly bandwidth cap, beyond which the phone company will pile on extra usage charges. When you exceed your monthly bandwidth cap, the costs can skyrocket and you’ll be looking at a large phone bill at the end of the month.

However, at this time, iPhone 4 allows video calls to take place only when you are inside an area that has wifi access (typically, your home or workplace wireless network).  Any traffic that goes over wifi network doesn’t count against your monthly bandwidth cap.  Only when you are out and on the 3G wireless connection will the traffic be counted against your monthly bandwidth limit. For now, for iPhone 4 users there’s no need to worry about your FaceTime video calls having an impact on your AT&T monthly bill.

It’s rumored that iPhone 4 will eventually be able to do video calls from wherever you are, even if you aren’t in a wifi zone.  Other advanced smartphones such as Sprint EVO can already handle video calls anywhere over the 4G network. This begs the question: How many video calls can you make before you hit the monthly bandwidth limit and before you get charged additional fees?

For example, AT&T offers two possible data usage plan for the iPhone 4:

$15 for 200 MB/month
$25 for 2 GB/month

Typically for a call with good quality video, the call requires a bandwidth of 384 Kbps.  How does this translate into video call minutes?

At 384 Kbps rate, the video calls will consume 2.75 MB per minute.

On the 200MB/month plan, the plan would allow 72 minutes worth of video calls per month.  With the 2GB/month plan, it allows almost 12.5 hours of video calls per month.

Also note that these calculations doesn’t take into consideration all the other activities you may like to do on the smartphone, such as email, SMS, instant messaging, web browsing, watching or uploading photos/videos, etc which would also count against your monthly bandwidth limit (when not on a wifi network).  Also, video calls may not be running at 384 Kbps, but depending upon the video calling app itself, the rate could go lower to the minimal acceptable video quality at 256 Kbps. At this lower rate, there would be an increase in available time for video calling.

Everyone uses their phone in different ways so the above numbers for video call minutes can be taken into consideration when determining which monthly plan fits you the best. Of course, for the iPhone 4 users, all this is moot until FaceTime app is capable of making video calls outside wifi zones and on 3G/4G wireless networks.

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