What is SMSC
Short message Service (SMS) is one of the widely accepted wireless service that enables transmission of alphanumeric messages between mobile subscribers and External short message entities. SMSC is an abbreviation for Short Message Service Centre. It is a comprehensive solution which includes the hardware and software for storing and forwarding Short Messages
Who uses SMSC , How Mobile operators generate revenue
Mobile operators charge for SMS delivery services. Usually, SMSC supports below operation modes
- Mobile Originated, Mobile Terminated (MOMT)
- Mobile Originated, Application Terminated (MOAT)
- Application Originated, Mobile Terminated (AOMT)
- Application Originated, Application Terminated (AOAT)
Mobile Subscriber Level - When a mobile subscriber sends a message to another mobile subscriber or application, mobile subscriber gets charged for the SMS delivery services offered.
Application Level - Corporate users connect to SMSC for various messaging needs such as for Advertisement messages, Bulk messages, Service notifications etc. Such corporates are charged by mobile operator for SMS packages and messages delivered to mobile subscribers or applications.
SMSC in GSM architecture
- MS – Mobile Station ,
- MSC – Mobile Switching Center
- HLR – Home Location Register
- SS7 – Signalling System 7
- SIGTRAN – Signal Transport
- SMPP – Short message Peer to Peer
- ESME – External Short Message Entity
- SMSC – Short Message Service Center
On the external applications, connection to SMSC usually is over two popular protocols i.e. Short Message Peer to Peer (SMPP) and HyperText transfer protocol (HTTP) over TCP / IP . Some SMSC vendors like Nokia support CIMD2 protocol which is not much popular nowadays.
SMPP is one of the standard protocol used by applications to connect and submit messages. There are few popular open source SMS gateways such as Kannel gateway , Jasmine gateway etc supporting SMPP encoders and decoders which applications use to interface with SMSC and their application over APIs.
Some of Major features of SMSC
· Delivery of SMS
Primary function of SMSC, enabling delivery of message from a mobile subscriber to external application and vice versa.
· Retry, Store, Forward SMS
During instances of unsuccessful first attempt delivery for reasons such as mobile subscriber out of network reach, handset switched off, external application not present etc the message is stored for a defined validity period and reattempted at intervals as per the message delivery attempt retry configuration. If even after maximum retry attempts, message delivery is not successful or the maximum validity period reaches, such messages get deleted
· Delivery Status Reports
Delivery Status report (DSR) if requested by originating mobile subscriber or external application are generated. DSR gets generated on both either successful or failure of message delivery
· SMS routing
Routing of SMS from one SMSC to another SMSC or equivalent SMS Router nodes based on specific destination routing rules
· Barring SMS
Blocking an SMS from source or destination based on mobile number, location
· Time based message delivery
Attempting / Blocking of delivery of messages during specific time of the day, day of the week , day of the month , special days
· Quota Management
Allocating a specific quota or package of SMS to mobile subscribers or applications for a particular day / week / month restricting the throughput and traffic across client applications
· Charging, CDR, Closed User Group (CUG)
Prepaid and Post-paid charging on message attempt / delivery. Special tariff for subscribers who are part of the closed user group. Subscribers may opt-in and opt-out from such groups using specific keywords. Charge detail records (CDR) for billing needs with information on source, destination, time and location details.
· Distribution List
Segmenting specific subscribers lists, common faster methods of message delivery to all subscribers in the distribution list
· Priority based message delivery
Allocation of priority to messages such as Emergency, Normal, Important etc and prioritized delivery. For example, application sending an OTP message may carry a higher priority than normal advertisement message.
· Various message types
By default, in a single SMS maximum 160 alphanumeric characters are allowed. Utilizing the handset capability of concatenating SMS, more than 160-character length message may be supported. Some of the message types supported by SMSC are
- Concatenated SMS
- Binary SMS
- Ringtone, Logo messages
- Unicode messages for sending message in different languages
- Flash SMS
SMS Limits
In one SMS , maximum
- Standard SMS – 140 octets or 160 ASCII characters
- Unicode SMS – 70 characters