Don't have an SMS-ready cellphone yourself? You can e-mail from a computer to an SMS-capable phone. Here's E-mail to SMS addressing for major carriers:
For example, to SMS someone on T-Mobile with a phone number of 202-456-1212 send an email to firstname.lastname@example.org
1. You need to know what carrier your SMS recipient uses (see FoneFinder- but that's not accurate in the event of number porting).
2. You must keep the message (including sending e-mail address and subject) down to 160 characters.
3. Won't work to analog phones.
4. Won't work on some older digital phones.
Here are some multi-carrier and non-US eMail-to-SMS gateways.
This has the advantage of rejecting your transmission right away if the carrier for the receiving phone ain't what you think (a real problem Stateside with Number Portability). Here are some websites where you can prepare and send SMS messages to mobile phones.
Google - requires you know the destination carrier
Vazu - All carriers
Teleflip - All carriers (but see above privacy risk).
Virgin Mobile USA representatives say if you use any of the above web pages to enter a text message, it should get through. Their own texting web page is available only to Virgin Mobile users, who can reach it by starting here, and entering their mobile number and password. Click on Ringtones and More on the menu bar near the top, then scroll down to Messaging to enter a text message.
If you need to do a lot of this, Open Source SMS software for Windows and many apps for Linux are available, as well as a lot of commercial stuff.
And, now the other way; phone to e-mail
Some carriers permit messaging from mobile to e-mail. Forex, T-Mobile users can send an SMS to address 500. The first string, up until there's a space, is the e-mail address(es) to send to. The second sting IF ended by a # is the subject; otherwise, if the second string is not ended with an octothorpe (yeah, that's the name for a #), the rest of the text is message.
so, an e-mail sent by SMS looks like this on the mobile:
email@example.com Ummagumma# Now is the time for all good bricks to fall from their wall.
and arrives as:
Now is the time for all good bricks to fall from their wall.
The gateway address will vary from carrier to carrier, and I regret I don't know it for all major carriers. I also have not tested the second-string-ending-with-# feature on Cingular/ATTWS. So, I have:
For Sprint, try entering the email address instead of a mobile number. (J. P. said it worked with his Treo 650.)
For Verizon, put the email address in the "To:" form. (Thanks to D.C. who provided this tip.)
Virgin Mobile has their own similar procedure here:
Select an email address from one of your contacts, or enter a new email address in the Send To field. To enter text, click on the ABC button. Then select Normal Alpha. To enter the "@" symbol, choose Symbols from within this menu.
Once you have entered the email address, hit Next. Then, enter the message and hit Next/Send.