SMS (Short Message Service)

Short Message Service (SMS) is a text messaging service component of most telephone, internet, and mobile-device systems. It uses standardised communication protocols to enable mobile devices to exchange short text messages. An SMSC is used to relay SMS from the sender to the recipient.

Detailed information on SMS can be found in the Melrose Labs SMS reference section.

SMS Character Limit

SMS on GSM-based mobile networks has a limit of up to 160 characters when using the GSM 7-bit default alphabet or 70 UCS2 characters (e.g. for Arabic and other non-Latin languages). When a message is longer than these limits, then a "long SMS" (or concatenated SMS) can be sent that uses segmentation and reassembly (SAR) to split the long message into multiple SMS message parts that use meta data to associate the parts. SMS can also carry non-text message payloads up to 140 x 8-bits in a single message.


When sending an SMS from one mobile to another, the sending mobile passes the SMS to their own mobile network's Short Message Service Center (SMSC), and this stage is known as the Mobile Originated (MO) SMS. The SMSC then attempts delivery of the message to the destination mobile, which may be on the same network or another interconnected mobile network. This latter stage is known as Mobile Terminated (MT) SMS.

SMS is defined in the 3GPP Technical realization of the Short Message Service (SMS) standard (23.040).

Melrose Labs Tyr SMS Gateway

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