Need help/suggestions for GSM auto-dialer in alarm system

[Wilsas]

Hello everyone,
I am unsure if this is a noob question/request or something more advanced.
So here goes.
Basically i need some kind of automatic switch which would work with ~2Hz interval once it gets powered with 12v.
I already tried combining a relay with a cap like shown in this video: GSM ?? ??.
Yet i miserably failed. I have no clue to why the relay just outright refused to go slow enough or change the switching speed at all.

After that i started thinking about 555 timer and using only solid state components. But a single simple relay with a cap would be perfect (if it worked like in the video)

To sum it up, I need some kind of circuit, which, when powerd by 12v from a motion sensor, would trigger a phone call (press call button twice). #1 priority is reliability #2 priority is price (the lower the better)
I am open to suggestions and am willing to learn something new in the progress of making this work!

P.S.
This would be just an addon to an already working alarm system.

[G7PSK]

What you have in the circuit shown the relay will only switch at the speed that the mechanical parts can move most likely quite fast giving a buzzing sound, the capacitor is only for spark, rf suppression.
To change the switch speed you need to do something along the lines of put the relay coil across a capacitor and then connect that to the supply through a resistor and arrange the relay contacts such that when the relay switches it discharges the capacitor.