How many users or extensions do I need?

User versus extension versus line

A user is a person with a login, voicemail box and the ability to use the apps. An extension is a number you can dial internally; every user has one, but an extension can also belong to a shared phone with no person attached. A line, in the old sense of how many calls could happen at once, is no longer something you buy; a cloud system handles concurrent calls without a fixed line count.

• User: one per person who needs their own calls, voicemail and app.
• Shared extension: a phone in a place rather than for a person, for example reception, kitchen or shop floor.
• Ring group or queue: a rule that rings several users; no licence of its own.
• Main menu and voicemail boxes: features, not users.

A quick way to count

• List everyone who answers or makes external calls as part of their job.
• Remove anyone who would only ever use a shared phone.
• Add one shared extension for each physical phone that is not tied to a person.
• Decide whether part-time or seasonal staff need their own user or can share.
• Leave room to add users later; you are not locked to the initial number.

Examples

A five-person accounting office with a receptionist: five users, no shared extensions. A dental clinic with two front desks, three operatories and four staff who take calls: four users plus five shared extensions. A trade company where the office manager answers and eight technicians only need the mobile app when on call: one user for the office manager, plus a user for each technician who should receive direct calls on the business number.

Your specialist confirms the count during planning, and the quote lists each user and shared extension separately so you can adjust.