Apple's iTunes Match service is running up cell-data charges for some unsuspecting iPad users.
For $25 a year, iTunes Match stores your iTunes library on Apple's iCloud servers and makes them available on any PC, Mac, iPad, iPhone, iPod Touch, and other iOS devices. CNET blogger Lance Whitney in a December 28, 2011, post; Apple provides an iTunes Match FAQ.
When I signed up for the iTunes Match service, it took several hours to upload via a cable-modem connection about 5,500 MP3s that were stored in the iTunes Library on a Windows 7 PC. Once the transfer was complete the MP3s were accessible from iTunes on my iPad; I also tested iTunes Match on a Mac. On the iPad and the Mac the Matched tracks played after only a slight delay.
In addition to songs and other media purchased from the iTunes store, iTunes Match works with music tracks ripped from CDs as well as MP3s converted from audiocassettes, LPs, and other analog sources. I was pleasantly surprised to find the service retrieving album art for songs I transferred from cassettes and records using the free Audacity audio software; I explained in a post from last July.
Matt Elliott provides ain a November 15, 2011, post on the CNET How-to page.
Default iTunes Match setting can lead to jumps in cellular-data use
Last week a friend of mine found that just a few days after purchasing the iTunes Match service in December she had exceeded the monthly data-transfer limit on the AT&T cellular plan for her iPad. In previous months she had barely approached the limit. She was unable to reach AT&T support to ask what had caused the spike in cell-data use, but a salesperson at her local Apple Store determined that the increase was due to an iTunes Store setting on the iPad.
When you activate iTunes Match on an iPad or other iOS device with cellular data plan, the service pushes updates from your library to the device via Wi-Fi. However, when a Wi-Fi connection is unavailable or closes, such as when the device enters sleep mode, the service switches automatically to downloading updates through the machine's cellular connection. The Apple Support site explains how push notifications use cellular data on iOS devices.
Since my friend had purchased several movies on iTunes, the service was attempting to push these large files to her iPad. According to posts on Apple Support Communities, even shuffling your songs can cause iTunes Match to push updates to your devices. If you're not on a Wi-Fi network, the service will use the device's cell connection if one is available. As you can imagine, this feature has caught many iTunes users offguard.
With considerable effort my friend was able to reach human beings at AT&T to explain the problem and obtain a refund for the inadvertent cell-data charges. She also reset her iPad to prevent background updates of the device's iTunes Library using AT&T's 3G network.
As a post on the MacRumors Forum indicates, iTunes Match changes the setting under Settings > Store > Use Cellular Data to "Use cellular network for iTunes Match and to automatically download purchases." (Disabling iTunes Match's cell-data use on the device reverts the setting to its original form, as shown below.)
The simplest way to prevent iTunes Match from using your cell-data connection whenever a Wi-Fi link isn't available is to disable the service's use of the iPad's 3G network: click Settings > Store and set Use Cellular Data to Off. Alternatively, you can disable all cell-data transfers by choosing Settings > Cellular Data on the iPad or Settings > General > Network on the iPhone and switch the Cellular Data setting to Off. Of course, you'll have to turn the setting back on whenever you want to use the device's 3G connection to transfer data.
The questionable utility of AT&T's 250MB-per-month iPad data plan
Several people posting to Apple Support and other forums about iOS devices automatically switching from Wi-Fi to 3G connections question the usefulness of AT&T's cheapest $15-per-month data plan, which limits transfers to 250MB per month. The company charges an additional $15 for each 250MB customers use above the limit in a 30-day period. The $25-per-month plan allows up to 2GB of data transfers per month and charges $25 more for each additional 1GB of use per month.
Some iPhone users are surprised at how much more data their iPad apps use compared to their iPhone counterparts. That's why it can be a mistake to base your iPad data needs on the amount of data transferred to and from your iPhone. If you opt for AT&T's $15-per-month 3G plan for the iPad, you'll likely need to set the device to restrict manual cell-data transfers. Either that or resign yourself to the company's monthly over-limit charges.