Just call maxis:

1. Ask maxis to convert all ur supp line into principal line, then only port out all number. U will be charge pro-rated in final bill, or

2. Ask maxis to convert all ur numbers to prepaid. U need to topup to use data/call. Usually prepaid is faster to port out than postpaid.

And yes, maxis can convert postpaid to prepaid (or vice-versa) by just calling them.