Question on System Requirement

Question

I have a scenario where a specific webservice must be consumed based on the state to setup user info. For instance if the state is NY or NJ call service A , if state is WA call service B etc. But specifying what service must be called is I guess is "HOW" to setup a user info and not a "WHAT".

So should I just have single requirement stating system must have the capbality to setup up user info based on state?

EDIT: I would also like to add that the services implemented for different states might want different info to be provided in addition to basic details such as first name and last name. Should the services , input to the services , output from the service , what the program needs to do with the output etc be part of system requirements? I guess all these deal with "HOW" more than "WHAT" - hence is it in the requirements realm?