re threat using sms

I feel for your problem (if it is indeed your problem).

Just as with a verbal threat, you can't take the law into your own hands.
In this day of easily swapping out cheaply-bought SIM cards, backtracing
an SMS message via requestwith the cell provider might not be productive.
Worse still is the ease with which an SMS message can be sent via internet
(from a rented terminal in an internet-cafe, even).

Maybe you can use this problem to your advantage:
If all the sender has is your cell number, then you can change it easily.
If on the other hand, the harrasser has your address and other details,
vigilance and the means to protect yourself are the answer.

You can file a complaint with the police so that it becomes a matter of record.
This might help with processing a carry permit, if you don't have one already.
Texted threats are almost always empty. Someone serious about harming you
would not likely do you the favor of letting you know in advance. There are
exceptions, but in any case, you should do nothing that would escalate the
situation.

JM2, and I'm sure others will have their own thoughts on this.
God keep you and yours safe,

h.