What is SMS?

SMS (Short Message Service) is part of the GSM and PCN standards which allow up to 160 characters of text to be sent or received by a mobile terminal (cellphone). This is similar to using the phone as a text pager.

The SMS message is sent to an SMSC (Short Message Service Centre) belonging to your mobile network. This is a computer which stores the message until it can be delivered to the recipient. Messages can be sent to the SMSC either direct from a mobile phone (SMS MO- Mobile Originate), or via a dial up connection using a modem and a computer.

The SMSC will store the message if the recipient's phone is out of coverage or turned off. The message will automatically be delivered when the phone comes back into service. Messages can have an expiry time set, in which case the message will be deleted if it has not been delivered at the end of this period. For dial up messaging, the expiry time is set by the network, and varies from network to network.

Some examples of when SMS may be useful :-

  • when the phone is not within a service area (the network will send the message when the phone comes back within the service area)
  • when the phone is not turned on, and voice mail is disabled (SMS is always enabled, as long as it is supported by the network operator)
  • for sending detailed information to the phone user (addresses, specifications etc) without the user needing to write them down
  • to send the same message to a large group of people (eg new prices to sales staff, notification of a meeting date)
  • to send an unobtrusive message when a phone call would not be acceptable (eg to someone in a meeting).

Do I need a special phone to use SMS?

Not all digital phones are capable of transmitting SMS messages, but most current digital phones can receive them (as long as the network operator has the facility enabled). Note that with some network operators, users may have to be connected to a certain tariff to have the send facility enabled, but they may still receive messages.

Will this work outside the UK?

Whilst roaming in another country using GSM, the SMS message will still be delivered if the network that you are roaming on has the facility enabled for roaming users. Depending on the roaming agreement, you may or may not be charged for reception of these messages.

SMSMaster can send messages to users of non-UK networks by routing them through Vodafone or Cellnet's Short Message Service Center. You thus only pay for a UK call to send a message internationally. SMSMaster can be configured to dial into non-UK networks, as long as the message center uses TAP (Telocator Alphanumeric Protocol).

How are the messages stored? How many are stored?

When a message is received by the phone, it will be stored in the SIM (subscriber identity module) smart card, and will be available to be read whenever needed. It will be saved until you delete it, allowing use as a simple notepad. Most phones can be configured to beep when a message is received, or just light up an indicator on the display if beeping would be unacceptable. Depending upon the phone and the SIM, you can usually store between 5 and 15 messages.

Why use a software package like SMSMaster?

Given that not all phones can send the messages, and that it is not easy to type a message into those phones that can, this technology can best be exploited using a computer and a modem. The computer can maintain a set of standard messages together with a phone book, and provide an easy and intuitive user interface. The messages are uploaded via a modem to the SMSC (Short Message Service Centre) of the network operator of the phone you want to page. The only charge for this is the call to the SMSC, which is usually charged as per a call to a mobile on that network. The person receiving the message does not have to pay anything, unlike the standard voice mailboxes provided by the networks. (The receiving party may be liable for reception charges in countries other than the UK).