GSM Intruder Alarm Sim

yaz2010

Hi members,
I have got a intruder alarm fitted with a GSM dialer.
I had a three pay as you go sim in an iPhone which I tried to use in the alarm , however it is not getting any signal. Alarm box is on the groundfloor.
I have ordered pay as you go sim from Vodafone, Giffgaff and Virgin to check if the GSM dialer would get signal.
I am just wondering is there a special sim for the intruder alarms.
Based on what I read , I called 3 to deactivate voicemail and still GSM dialer does not get any signal.

Could you please provide some comments ?

Thank you.

forgotmyname

How long did you leave it? Tried a 3 sim in an old phone the other day.

Although text messages were being received to say its all working you could not ring the phone for several hours.

So popping a SIM in wont be an instant working. It needs to register on the network. And it may attempt to send settings to the device?

Not sure how that works, But this phone had several texts saying open and then restart the phone.

If you put your phone in the same location is there a signal?