I have a problem with my answering machine and telemarketers. I have a Casio cordless phone with digital message machine built in.
Recently my machine has been filled up by telemarketing calls. What happens is this. My machine picks up the call and plays my recorded message. After the beep a recorded voice says something like ‘Please hang on while we connect you to the next available operator for a special offer’. The problem is that my machine keeps recording and the telemarketers machine keeps the line open. It eats up all the memory for legit messages.
I have missed important messages because of this.
How can I stop the telemarketers from eating up my answering machine without buying a Tele-Zapper or what ever it is called.
Slee
You could simply record the tones that the tele zapper uses on your message:
http://www.flash.net/~carlton2/telemark.htm
I use a long but
a) amusing
or
b) suicide-inducing
song snippet on my broadcast - very few sit through it, for some reason. 
Just out of curiosity, what song?
Life Is A Toil - as performed by Ronnie Gilbert and friends, from Songs of the Working People (From the American Revolution to the Civil War) (Flying Fish, cat FF70483, 1988).
I have also heard Pete Seeger perform it.
I vary it with the line from the Weaver’s version of Goodnight Irene (box set):
“Sometimes I live in the country,
Sometimes I live in town.
Sometimes I takes a great notion,
To jump into the river and drown”
(I will leave it to the reader to decide if this verse is the origin of the book/movie title Sometimes A Great Notion 
).