You may need to adjust a setting on your iPhone before you can use iTunes Match when not connected to a Wi-Fi network.
If you subscribed to iTunes Match and got the service set up and running on an iOS device, there might be one more step required before you find yourself rocking out from the cloud.
Yesterday, I gotiTunes Match set up, but I did so while all my devices were on my home Wi-Fi network. Today, I ventured to my local bagel shop and tried connecting to iTunes Match from my iPhone. When I tapped on a track to begin playing an album, I received an abrupt message: Cannot Play. It instructed me to connect to Wi-Fi network or enable cellular playback in Settings. Enable cellular playback? This was not a setting with which I was familiar.
Here's where to find the setting: go to Settings > Store and then turn the slider on for Use Cellular Data. Now, you'll be able to download and play songs from iTunes Match on your iPhone when you stray from a Wi-Fi network. Grabbing songs over your iPhone's 3G connection will count against your monthly plan, so proceed with caution. Remember, songs are downloaded and not streamed to your iPhone, so if you are up against your data limit, it might be a good idea to download an album or two over a Wi-Fi connection before you leave the house. Then, you can play the locally stored copies without adding to your data usage.