SMSC

A short message service centre (SMSC) is an element of the mobile telecommunications networks which stores, forwards, converts and delivers SMS messages and maintains unique timestamps in text messages.

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 and forward the message when the recipient is available or when the message's expiry period has been exceeded.