On 14 Feb, 13:51, "Jack" wrote:
Get an old cassette type telephone answering machine at a thrift store.
These have dial tone decoders to play back messages when you punch in your
playback code from a remote phone.
Hack into the answering machine and find the playback signal and use it to
latch a relay controlling your pc.

Jack, i like your thinking - clever use of existing technology.