SMS Forum
The forum covering all aspects of SMS messaging.

What is SMS?

SMS (or Short Message Service) is a means of communicating short text messages with mobile phones. Messages can be sent between mobile users' phones or between applications (e.g. voicemail systems, retail websites, banking systems) and mobile users' phones.

SMS in use on GSM mobile networks supports up to 160 characters when using the GSM 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).

For information on concatenated SMS (aka long SMS), there's a good resource on Wikipedia: Concatenated SMS.

SMS

SMS Testing

There are a number of free services available online for use in SMS testing. These cover SMSC simulators, protocol conformance, application stress testing and other areas. Some are listed below:

SMPP

Specifications and services directly related to the SMPP protocol, the SMS-specific protocol for enabling SMS in applications.

SMPP Protocol Specifications
SMPP Protocol Specifications

SMPP (Short Message Peer-to-Peer) is an open, industry standard protocol designed to provide a flexible data communications interface for the transfer of SMS.

SMPP SMS Gateway
SMPP SMS Gateway

Cloud-based high capacity and high reliability SMPP SMS Gateway platform with advanced routing. Supports A2P and P2A SMS.

SMSC Simulator
SMSC Simulator

Cloud-based high capacity and high reliability SMPP SMS Gateway platform with advanced routing. Supports A2P and P2A SMS.

Tyr SMS Gateway
Tyr SMS Gateway

Global SMS gateway supporting SMPP v3.3, v3.4 and v5 for SMS delivery globally.

Services: Mobile Marketing with SMS, and other services

SMS text marketing (#martech). Virtual Mobile Numbers. Virtual SIM Hosting. SIM Hosting.

webSMS
webSMS

Web SMS service for sending and receiving SMS.

UK Telephone Numbering

The following numbering from Ofcom is accurate as at Tuesday, 19 March 2024.

UK 01 and 02- Prefix
UK 01 and 02- Prefix

Geographic Numbers

UK 07- Prefix
UK 07- Prefix

Personal Numbers, Radiopaging Service & Mobile Service numbers (mobile numbering).

Mobile Network Codes ("MNC")
Mobile Network Codes ("MNC")

Mobile Network Codes (MNCs) for the UK

Numbering Transactions
Numbering Transactions

Numbering allocations over the last 12-months

Mobile Network Operators

European Mobile Network Operators
European Mobile Network Operators

List of mobile network operators of Europe

Mobile Country Codes
Mobile Country Codes

MCCs for mobile network operators

Mobile Numbering by Country
Mobile Numbering by Country

List of mobile telephone prefixes by country