SMSC

SMSC stands for 'Short Messaging Service Center' which is responsible for handling the SMS operations of a wireless network. Although this is a relatively smaller topic it is important to know what it does when it comes to learning mobile operations. 

Whenever we send an SMS from the mobile phone, it is sent to the SMS Center first. The SMS center is liable for sending the message to the correct destination. Depending on the status of the destination mobile phone, the SMS will be handled accordingly. For example, if the Receiver's mobile is offline the SMSC will store the SMS message until it is switched on and will send it once the user is available. This process is called as a store-and-forward option and is used to regulate the sending of SMS messages. An SMS message might need to pass through more than one network entity (e.g. SMSC and SMS gateway) before reaching the destination.

The SMS traffic of one wireless network is handled by one SMSC, most of the time. Network operators usually manage their own SMSC(s) and locates them inside their wireless network system. However, it is possible for a network operator to use a third-party SMSC which is located outside its wireless network system.

In order to use SMS messaging with our mobile phone, we must know the address of the wireless network operator's SMSC. Typically, an SMSC address happens to be an ordinary phone number in the international format. A mobile phone should have a menu option that can be used to configure the SMSC address which is usually pre-set in the SIM card by the wireless network operator, meaning that we do not need to make any changes to it.

Some of the SMS Center Services which we can configure via the mobile phone settings and request are,

1.  Validity Period of an SMS Message - An SMS message is temporarily stored  in the SMS center if the mobile phone of the recipient is switched off. It is possible to specify a cutoff/expiration period after which the SMS message will be deleted from the storage of the SMS center. Once deleted, the SMS message will no longer be available for dispatch to the mobile phone of the recipient(even if it becomes online).
2.  Message Status Reports - To notify the SMSC that we are expecting a message delivery report, we need to set a flag in the SMS message which will notify the SMS center that the Sender is requesting a status report. This status report is sent to the SMS sender in the form of an SMS.

However with the emerging technology, many telephone companies want to integrate messaging infrastructures to IP networks, that are designed to carry messaging traffic. In addition, mobile operators are looking to reduce costs and improve their network's quality in order to maintain customer satisfaction and reduce churn. 

Consequently, mobile messaging infrastructure companies have started providing platforms that will have more efficient messaging delivery and capacity services with SMS routers which some SMSCs were unsuitable to deliver, including group distribution lists, copying, forwarding and archiving messages, and extras, such as anti-spam functionality.