SMS centre is a network element in the mobile telephone network to store, forward, convert and deliver Short Message Service (SMS) messages. When a user sends a text message (SMS message) to another user, the message gets stored in the SMSC (short message service centre), which delivers it to the destination user when they are available. This is a store and forward option. When an SMS message is sent from a mobile phone, it will reach an SMS centre first. The SMS centre then forwards the SMS message towards the destination. The main duty of an SMSC is to route SMS messages and regulate the process. If the recipient is unavailable (for example, when the mobile phone is switched off), the SMSC will store the SMS message. It will forward the SMS message when the recipient is available and the message's expiry period is not exceeded.