Telemarketers have been annoying me for the last few months. They call my Fido
mobile phone with an automated dialler that has an automated voice message. It
starts out something like This is not a sales call. This is a very
important call.
. They then provide a phone number to call back and some sort
of tracking number. I did a little investigation and found that they are
probably a mortgage broker and are not inside Canada. They have been calling
my phone every few days. Often they will leave a voice message which I have to
waste time deleting.
A few days ago I decided to try the SIT trick. The idea is to prefix your regular voice message with a SIT and
that will cause the telemarketer's automated dialler to hang up, maybe even mark
your number as out of service. I searched around a bit but couldn't find a good
quality tone. I found a Cisco manual that provided SIT specifications and created my own audio file.
I generated the vacant circuit
tone:
- 985.2 Hz for 380 ms
- 1370.6 Hz for 274 ms
- 1776.7 Hz for 380 ms
I left about a 3 second gap between the SIT and my regular voicemail
greeting. I was worried that the quality may not be good enough but it seems
to have worked. I got about two calls after adding the SIT that did not
provide Caller-ID information. I sent them both to voicemail instead of
answering. Since then I haven't got any telemarketing calls. I would provide
the audio file but I seem to have deleted it. It can be easily
generated using Audacity.