Bro, kindly provide smart watch model or some specs so that the sifus here know which telco service is suitable ...

Most of the cheap ones only uses 2G and the better ones on 3G ... the gps doesn't need data, it only needs gps satellite locking (yeah, basements is a no-no) ...

As of today, the most cost effective prepaid sim for generic kids gps smartwatch is Altel (rm28 annually). If the kids gps locater requires high speed data for whatever then your telco choice will broadens abit ... but bottom line depends on the kids smart watch specs ... if it doesn't support the telco band then no use getting the sim ...

Ok, lets see ... the smart watch is supposedly Mediatek 2503 based, so according to the datasheet it's 2G band + GPS + LBS ...

If you're getting this kids watch then look for Altel prepaid (RM7 RRP) and comes with :
- RM3 credit
- 200mb data (valid for 15 days)
- 30 days active validity
- Basic internet 64kbps
- celcom network

At the end of 30 days, topup RM30 and buy 1 year validity (for RM28) and yes, you still get basic internet for a whole year.

If you can't find Altel in your area then check out onexox with season pass as the next best option. Anything more than Altel and onexox is arguably a waste for a kids watch. If you insists on something else then ensure the telco works on 2G band. Whats 2G band? ... well remember nokia 3310 phones ?

I don't know what's the variable with your area .... the areas that I frequented to have no problems with celcom 2G signals (including indoors) ... I have an old nokia 2G phone and older androids with 2G only slots that works fine with C, D and M telcos ...

Seems similar to the previous device ... bear in mind that most china made kids watch uses mediatek chipsets and thus have similar performance.

Regarding the possible poor 2G coverage mentioned above, you may want to try out the sim with an old phone in 2G mode at the places that your kid(s) frequented to ... that shoud give you an idea hows the reception would be like ...