I wouldn't call what you describe a network effect - it's a classic switching cost/lockin, but not a network effect.
A company with 5000 Box users is a single paying customer with zero network effect. It would be a network effect if there was some significant benefit for other companies (other potential customers) to start using Box (and not something else) in order to cooperate, but I'm not seeing that much.
A company with 5000 Box users is a single paying customer with zero network effect. It would be a network effect if there was some significant benefit for other companies (other potential customers) to start using Box (and not something else) in order to cooperate, but I'm not seeing that much.