Not real sure about this, but seems like "pre-payment" discounts would be dependent on conditions beyond the scope of MFL provisions. MFL ensures that you get access to the "same" licensing terms that anybody else obtains,... but you must meet the same qualifications.
IMO "rates" are one thing, while "pre-payment" terms are something else, i.e., you gotta "PRE" pay before you qualify. Seems like Nokia has a lot of work to do before they are going to qualify for any "pre-payment" discounts from InterDigital on their 3G IPR usage.