Sending SMS Messages to Landline Phones

Network Managers need to be alerted to problems on the network at all times. But how to achieve this? Sending emails is the most common method used, but what if the user isn’t at their machine, or it’s not switched on? In certain circumstances alarm bells or lights work well. Third party monitoring companies are excellent, give 24/7 coverage but are very expensive. Is there an alternative, cheap, reliable method of receiving alerts?

SMS Alerts

Mobile phones have the advantage of being always on (or at least many users keep their phones on all the time). Sending SMS messages to mobile phones is a well established method of raising alerts, and works very well, but can be unreliable, with messages sometimes arriving days after they were sent.

Landlines on the other hand are very reliable, frequently manned 24/7 but will not accept SMS messages. Until now. With an increasing number of operators now offering SMS to landlines it is now possible to SMS messages to fixed phone networks. This has the potential to be very useful for alerting purposes.

ES 201 912

The protocol which allows this has the snappy title of ETSI ES 201 912, the European Telecommunications Standards Institute (ETSI) approved standard that allows the sending and receiving of Short Message Service (SMS) messages on PSTN/ISDN networks.

In other words if your telecoms provider offers this service you can send and receive SMS messages on your mobile or on any fixed phone.

The method uses a standard voice call to carry the SMS text. In the UK, Germany, France, and other countries, the protocol used is known as type 1.

Protocol Type 1

Protocol Type 1 allows a standard message size of up to 160 characters, is compliant with GSM SMS services and can be used with mobile devices. Multiple messages may be combined to produce longer texts.

Hardware requirements

Any phone that is capable of Caller Line Identification (CLI) can display the messages as text, but the service is not limited to phones of this type. Even on older or more basic phones the messages will be automatically converted to a synthesised voice. This makes the service very flexible.

In the case of say a temperature monitor an alert is raised if a threshold is exceeded, the management software sends a predefined SMS message (using a dedicated SMS Modem) to a mobile or fixed line phone. If the phone is capable of handling SMS directly the text appears, if not then the message is read out by the automated voice.

Reliable

No-one would argue that this is 100% reliable then, but in most cases very good, low cost, easy to set up and very useful.

SMS alerting to landlines is a welcome addition to the Network Manager’s armoury.

About the Author

Denis Laverty possesses more than 17 years experience in network management and communications, Denis has been involved with network management applications from the early DOS days; as product trainer, technical author and QA Director. In 2003 he co-founded OPENXTRA together with Jack Hughes and serves as its Managing Director.