Oops.. SBS/ Toa Payoh area is 383---
They went by last time where you are at, like Boon Lay/ Jurong Ind
is 268---... Pandan if not wrong is 7----.... They go by where the
telephone exchange is at... By across 1 road can mean another
exchange 
Though these days if say move from Toa Payoh to Tampines I can keep
the number at an add cost...