Free SMS over internet.
An SMS can contain up to 160 characters (140 bytes), but it is possible to link several SMS messages to send longer messages
Benefits of SMS
Mobile. Messages can be sent and received wherever mobile coverage is available (even via certain landline and satellite telephones).
General occurrence. In principle, all mobile phones nowadays support SMS without any special preset.
Simplicity. There is no specific ”SMS address” to find out in order to send messages such as e-mail, all that is needed is the phone number which is usually already available.
Effective. The built-in limitation on the number of characters you can send along with a cost model where you pay per sent message leads to naturally short, concise and effective messages.
On the recipient’s terms. An SMS can be read and possibly answered when it best suits the recipient as it lies and waits on the phone when it is received.
Discreet. Works often in contexts where talking on the phone is inappropriate, e.g. at a meeting, a cinema or at a poor reception.