What is short message service center (SMSC)?
The short message service center (SMSC) is the portion of a mobile phone network that handles text message operations. It is responsible for receiving, storing, routing and forwarding SMS messages from mobile handsets. It is also called a short message service-service center (SMS-SC).
All text or SMS messages involve one or more SMSCs. In a typical message flow, the handset sends the message to the SMSC, which responds with a message indicating it accepted the SMS. If the recipient is not on the same network, the message is forwarded to the correct network's SMSC. That SMSC then determines if the recipient's handset can receive the SMS. If it is not available, the SMSC stores the message and sends it once the recipient is online.
The SMSC works with the other components of a mobile network -- including the home location register, the visitor location register and the mobile switching center -- to determine if the recipient is online.
The SMSC also works with SMS gateways, which enable text messages to travel between networks and into different applications. For example, SMS messages can be sent and received by email or automatically sent by programs. SMSC also enables SMS to be integrated into line-of-business applications, enabling organizations to use SMS for sending alerts, notifications or marketing messages.
The SMSC also determines the validity period for storing messages. As an optional request, the sending handset can tell the SMSC how long it should store a message. The carrier configuration sets the retention policy, which the SMSC enforces. Once the validity period ends, if the SMSC cannot send the stored message successfully, it deletes it.
How does a short message service center work?
The SMSC receives, processes and sends short messages. It is in constant contact with user handsets, sending messages indicating a successful delivery, a delivery failure or some other status information.
The SMSC uses a store-and-forward process to temporarily hold messages and then deliver them once a recipient's handset is back online. Business rules govern how long messages are retained in the SMSC before the message service deletes them.
In the case of bulk messaging, which many retailers and advertisers use, message aggregators send these messages through a gateway and into the SMS service for mass distribution to recipients.
The SMSC uses various techniques -- including message encryption, authentication and intrusion detection -- to ensure the security of messages in transit and storage.
At the detail level, the SMSC queries databases, including the Home Location Register and Visitor Location Register, when verifying sender and receiver phone numbers and checking on which mobile networks these phone numbers reside. It uses the international telecommunications Signaling System 7 protocol to set up, manage and end calls. The SMSC also verifies that each message format is correct; for example, the message is no more than 160 characters long.
Types of messages handled by SMSCs
SMSCs must be able to handle a variety of different messages, including the following:
- Person-to-person. These are standard text messages that individuals send to one another.
- Application-to-person messages. These messages are sent from applications, services or businesses to individuals to provide services such as order confirmation or product promotions.
- Person-to-application messages. Users send messages to applications, services and businesses.
- Flash messages. Messages such as emergency alerts appear on the user's phone.
- Unicode messages. These messages contain special characters like emoticons.
- Premium messages. These messages are charged at a higher rate and manage billing and routing between senders and receivers.
What is a short message service center address?
Each SMSC has an address identifying it on the network. The SMSC address is in the same format as an international standard phone number. It is part of the mobile network provider's configuration and is included on the SIM card or in the network provisioning package when the phone is initialized. Typically, the end user should not need to set the SMSC used by the handset. What distinguishes an SMSC number from a regular phone number is that it cannot be called or texted directly.
How to find an SMSC address on Android and iOS
Android version compatibility became available in version 4.0, and users could check their SMSC numbers. However, beginning with Android version 11, some phone manufacturers have restricted user access to SMSC information. Users of newer phones should contact their carrier for more information.
Because iOS is a closed system with stricter security, Apple does not provide a built-in method for viewing SMSC numbers. Users should contact their providers for details.
SMSC security
SMSCs are part of a mobile network infrastructure and are highly secure. However, because SMSC addresses are publicly accessible, they are still vulnerable to SMS spam, spoofing and denial-of-service attacks that use message flooding to disrupt service for legitimate users.
Although SMS data is often encrypted, it can be transmitted and stored on the SMSC in plain text. Users should be aware that SMS messages can be intercepted and read.
The future of SMSC
Although users still send SMS messages, they are increasingly using alternative messaging apps that do not use SMS, such as iMessage, WhatsApp and Signal.
However, despite this, the overall use of SMS has not decreased significantly due to the increase in application-to-person messages. This includes the use of one-time passwords, two-factor authentication, text delivery notifications and automated real-time alerts, all of which can be sent through SMS messages.
With the rise of technologies such as edge computing, the internet of things and enterprise automation, SMS messages will continue to play a significant role in communications. In these scenarios, systems and devices capable of sending automated messages can inform users of network and system status, traffic and other alerts, and even provide up-to-the-minute data on personal health metrics.
Rich Communications Services is a newer form of messaging that includes more advanced features than SMS. Learn how RCS and SMS compare and the technical requirements for each.
