Here’s an interesting device that has home automation applications. The £80 Z-text SMS Modem allows you to sending SMS text messages over a normal fixed Line, so no SIM/contract is required, and also allows text messaging where there have traditionally been signal strenth issues on the GSM network.
Fixed Line SMS is provided by normal telephone operators, and offers the reliability that is expected of a traditional telephone line. It also offers the advantage of showing the senders normal landline number.
Fixed Line SMS involves no contract or subscription, it is charged by the telephony provider just like any other call. The cost per message is similar to the minimum charge for a voice call.
Z-text takes advantage of Fixed Line SMS. No internet access or pre-payment is required; texts are charged to the telephone bill, just like any other call.
The Z-text SMS Modem has the same AT command set as a GSM modem (GSM 07.05), which it can directly replace without modification of the host application in most cases. Text and PDU Mode are supported.
In addition to being a very convenient method of sending text messages, the Z-text SMS modem is ideal for reporting alerts from environmental and network monitoring systems.
Z-text is suitable for use with worldwide networks that have implemented Fixed Line SMS Protocol 1. These include the UK, Europe, Asia, South Africa, and Australia.”