Adv Coll Dunning vs Strategies

Hi All -

We are implementing Advance collections in R12.1.3. Our requirement is to send pre delinquent and delinquent dunning letters based on aging and also assign call back. Our customers are grouped into 4 tiers so we need different  scoring for these tiers as the dunning letters are different.

Do we need strategies for this or can setting up dunning plan alone can suffice.

Thank you