For mobile phone companies, charging for SMS messages is a tremendous scam . They get to charge you $5 a month, or 20¢ a message, for something that costs them less than a penny, even factoring in storage costs.
Personally, I use IM on my phone, and avoid SMS entirely. However, occasionally there’s a need to SMS someone who either doesn’t have IM on their phone, or doesn’t know how to use it.
It turns out that if you have an AIM (AOL Instant Messenger) client on your phone, you can send SMS messages and receive replies for free, easily, at least in the USA.
All you need to do is add the person as a contact, with their AIM user name being replaced by their mobile phone number in international format, with no spaces. So if their number is 512-555-1234, you enter a username of +15125551234 in your phone’s AIM client. You can then message this contact as if it was a regular IM contact, and AOL will handle conversion to and from SMS.
If your phone doesn’t have an AIM client, check and see if there’s an official one. If not, there’s a free generic J2ME AIM client that should work on most phones that aren’t totally obsolete or locked down.
Of course, if you know what carrier your correspondent uses, you can look up the equivalent e-mail address for their phone number , as the major carriers all have e-mail to SMS gateways for their own customers.
For messaging me, you can use Jabber or AIM–and I’d rather you did, because the scammers charge to receive SMS as well…