Jim Hamm sends some interesting how-to for users of iMessage. "One nice feature of iOS is iMessage. If both parties have a device (an iPhone or iPad) with iMessage then text messages can be sent to each other for free. This bypasses the carrier and no text message fee is encountered by either party.
"Apple has made it easy to determine if the message will be free for both parties. When you go to send an iMessage and tap the number (or email address) of the person you want to send the message to, take a look at the number or email's color. If it is blue it means both parties have iMessage and the text will be sent free of charge. If the color is green on an iPhone (or red on an iPad) it means the message will be sent as a regular text message and fees will be incurred by both parties. If one, or both, parties have already subscribed to and paid a monthly fee for text messaging, there won't be an incremental charge.
"Apple's servers know if both parties have the capability of iMessage. If, say, you have an iOS device and want to send a text message via iMessage to someone who doesn't have iMessage, then the color of the number will be green or red instead of blue. Both parties could incur a text message charge from their respective carrier.
"If you haven't tried iMessage, you might give it a try. A quick and easy way to communicate with someone. Remember, if it's blue it's free to do...(grin)."