If you think SMS is a very limited-use service, you're right. Things can get a littlew cramped when you want to write more than a very quick note in the 160 characters provided, or if you want to write an e-mail to someone but only have about 110 characters to do it in. Enter MMS.
MMS stands for Multimedia Messaging Service. It allows for much longer, larger messages, which can be 50 to 100 kilobytes in size compared to SMS's 160 bytes. Thus, MMS can easily be used for text-based email, sending ringtones, audio or even small photos over the air. The two problems with MMS are universalness and cost.
It's getting better, but right now MMS is limited to a comparatively small sector of the cell phone market, at least compared with SMS, which is nearly universal. Also, if you wanted to send a message from, say, a Nextel phone to a Sprint phone you would have to use the phone's email address and even then the message might not be received. This is because not all carriers have made their MMS service interoperable with every other carrier. Sprint, Verizon, Cingular, T-Mobile and US Cellular can share messages between themselves, but other carriers, such as Alltel and Nextel, can't.
Of all these carriers, only a few offer prepaid plans with MMS. These carriers are Cingular, T-Mobile, Virgin Mobile (run by Sprint) and Boost Mobile (run by Nextel). And Boost Mobile can't share its messages with the other three carriers. Also, Boost and Virgin Mobile only have a few phones that support MMS messaging.
As of right now, unlimited MMS plans are few and far between, probably because MMS messages are much larger than SMSes and thus can clog cellular bandwidth much more easily. The only prepaid plan that has unlimited MMS is T-Mobile To Go's Sidekick plan. Otherwise, MMS usually costs 25 cents per message to send and receive. T-Mobile To Go allows you to receive them for free and send them for much less, depending on what size of card you buy. More on that in another post.
What You Can Do
Because MMS has a much larger size limit for its messages than SMS, you can do many more things with it. Like SMS, MMS lets you send and receive e-mails. Unlike SMS, MMS e-mails can be as many as twenty-five pages long, enough for even those computer newsletters like Langa List and Kim Komando (I'll tell you about these later). Or you can send a picture or two, though they will probably be greatly downsized to 160x120 pixels or similar, unless they're already that small. So don't expect so be able to print an MMS photo, but they're fine for cell phone backgrounds. You can even send audio attachments, though they can't be very long or very high-quality since I'm almost positive that MMS only allows wave attachments, which can't be compressed. The last thing you can do with MMS is send ringtones. Not one-note ringtones mind you, but full melody ringtones, in MIDI format. So go ahead, send James Bond to your phone. Just make sure the ringtone is small enough for the phone to handle it (I'm pretty sure most phones top out at 15 or 16 KB). Just as you can send these things to your phone, so can your phone send text, pictures and sound to other phones (if your carrier is interoperable with the other phone's carrier) or any me-mail address.
So, just when you thought your phone was worthless because you couldn't get the full Star Wars theme song sent to it, you've been saved by MMS...at least if you're using someone like T-Mobile To Go. If you can't send or receive MMS, yes you're missing out but console yourself; one of these days...