Mobile phone perks

I currently got 3 lines from 3 different telco and the contract is ending soon. So I decided to test out how generous telco company is. My plan for each company is about the same. I contacted each company and ask for handset vouchers. M1 replied and offered me $60. Starhub replied and offered me 6 months waived of caller id. Singtel replied and offered me nothing. So from here, you can see that which one is the most stingy one.