[kijin]

If your signup process is understandably complicated and you require a minimum commitment of $2500/mo, then it's probably okay for you to tell potential customers to give you a call.

If your signup process can be automated and you only charge $25/mo, and you still tell people to give you a call, then you will lose business because 1) the friction of a phone call is worth more than the difference between your offer and a competing offer; 2) it's impossible to tell whether your offer is worth the friction in the first place, because your pricing is unknown; and 3) people just assume that you'll charge $2500/mo because that's the usual price point where people say "contact us". If someone else comes along and offers an inferior product for $35/mo, they'll get all the business because monkey psychology.