SMS: Short Message Service WHAT IS IT?
The Short Message Service (SMS) is the ability to send and receive text messages of up to 160 characters at a mobile phone. SMS was conceived as part of the Global System for Mobile communications (GSM) digital standard, originally only at 900MHz but later also at 1800MHz (also known as DCS1800), 1900MHz (also known as PCS1900) and 800MHz (E-GSM). You can therefore in principle use these facilities on any GSM or "Personal Communications Networks" (PCN, which is also GSM).

GSM and PCN systems are able to store SMS messages for deferred delivery. This means that if your handphone is out of range or turned off, your messages will be stored by your mobile phone operator and delivered to your handphone when it is in range or switched on again.

Having established that you have a suitable digital phone, you need to check the exact facilities offered by the phone and the network. SMS Mobile Terminated (MT) is pretty much ubiquitous unless you have a very old phone. This is the ability to receive text messages at the phone. SMS Mobile Originated (MO) is only on a few phones. This is the ability to send text messages from the phone. There are other ways to send SMS messages: the most networks have public dialup access.