Do you know perl?
I had same issue and I wrote a simple perl script that works as wake up service.
PERL is an interpreted language and so can be executed on Linux and Windows operating systems. Linux can interpret perl natively while for Windows you can download many free interpreters like Activeperl or Strawberry perl. To run the script you must use a third party server.
In my configuration the script runs on a linux server in background as a service and checks every minute the directory called "alarm", reads files and uses the file name as called number and checks the content to verify if is the time to call. At the moment the script uses SIP and handles 4 call responses: 404 user not found, 486 busy, 487 not answer and 200 answer ok. In every cases sends an email and deletes files. Only for the answer case plays a nice music.
Files have this particular format: file name is equal to calling party number and file content is the alarm time in 24 hours format with : as separator between hours and minutes.
e.g.
ext. 101 must be called at 8 am ---> write the file 101.txt with the content 08:00
ext. 101 must be called at 8:30 am ---> write the file 101.txt with the content 08:30
There is a limitation: if you activate the Authentication for SIP messages and there are more then two simultaneous calls, the script sends some INVITEs without authentication or with wrong checksum and so not all phones ring. This problem is under investigation.
Are you intresting?
Regards.
