Why so excited to pay tax? 

I wish I can do this too one day
2-3 hours in traffic does take a lot of mental strength to overcome tho.

u can receive call but expensive roaming charges will apply

best is to get a miss call from them and call back with ur malaysia line.

thats what i did when i was in your shoes.      

Can! Money can solve anything

Try talk to A , dont say u got other offer, find some good excuses

If it work,  then u r lucky

Else......

Even u dont want to go to A, at least let A know and find a replacement for u......
2nd option is still to sign for B , start work date one or two weeks later than A. So, u join A ,and resign immediately, normally probation period will need to serve one week notice only. So you still can join B later on.

3rd option, i saw someone did it before, sign liao nvr come to work, call also no answer, at the end boh bian, find replacement for him, luckily my boss got shortlisted few from the interview. That time small company, also nvr bother to sue that guy.....
P/s both option 2 and option 3 , not workable if u r permit holder. Dun simply do it, ur company may report to MOM, u may get blacklisted and difficult to get ur permit in future