Converting voice T1s on a DS-3 to PRI

I am researching T1 vs. PRI feasibility for a 100 seat inbound call center (order receipt). The prospective client is running on two DS-3s (switch diversity) with standard robbed-bit T1s.

I am investigating either ditching the DS3s and going to an individual PRI (more like 6-8 PRIs, still in diversity arrangement) solution…

… or …

… converting the existing T1/DS1 circuits on the DS3 to PRI.

Would that ‘change’ require different provisioning at the DS3 level or is the PRI/Robbed Bit option configurable at the DS1 level on a DS3?

Any advice would be greatly appreciated.