Teachers record the messages themselves, type a note which is sent as a mobile phone text message or read out by a computerised Scottish voice, as research by call centres shows that people find a Scottish accent reassuring.
Six schools are now using the new communications system Call Parents, which allows them to send out bulk messages to pupils' homes.
The service has been developed by Birmingham company Truancy Call and is based on an earlier programme used to notify parents when their children were truanting.
Stephen Clarke, director of Truancy Call, said: "We had calls from headteachers asking if we could make a system for telling parents about nice things at school as well.
"Letters home can just end up scrumpled at the bottom of a child's bag, and if you email parents you don't know when they will get round to checking their messages."
Some schools have used the system to inform parents that lessons were cancelled because of snow. At Park Hall school in Birmingham, the service was used during the Christmas holidays to keep parents informed about their children's skiing trip.
Schools need an internet connection to run the system, which costs pound;995 for the first year, and pound;500 for each subsequent year, plus approximately five pence for each message.
Mark Maybury, upper school progress manager at Park Hall, said the system was less time-consuming and more effective than other ways of contacting parents.
"The robotic voice is not too bad," he said. "It does sound like a computer, but parents have not complained about it, and some are used to it from the truancy calls."
He said Park Hall was planning to use the service this term for parents'
evenings and to let parents know when pupils were due to bring home their reports, so that they would be less likely to go missing.
See website: www.callparents.com