Some vendors have minimum purchase requirements in terms of seats, contract duration or monthly contract value
Vendors
Standard contract lengths can run from monthly to multi-year depending on the number of seats
Contract lengths
Pricing options range from per seat, per user, per minute, per concurrent user, per call and usage-based
Pricing options
Solutions will differ in their commercial terms
Be aware that each vendor has their own preferred way of positioning contractual terms. Some might become showstoppers for you. Here are some of the most obvious ones used for cloud based solutions:
