question

So I found this post, which I didn't see earlier, posted 2 months ago.  It also goes along with my question

Confused about adding user or phone or ??......
Our system has three aspects to a user extension. There's the user extension itself, direct phone numbers, and digital lines. User extensions are just the shell for the user. The user extension is where you define things like user hours, passwords, call handling, and greetings. It is also where the voicemail is stored, so you don't actually need a phone number to get voicemail. 
Direct numbers are simply phone numbers that tell the system where to send a call. They don't have the ability to dial out on their own, but can receive calls. If the extension only has a number you need to either have a cell phone set up to ring in the user's Call Handling & Forwarding, or they need to be logged into the RingCentral app (desktop or mobile). If they're logged into the app though they can't make direct calls out if they only have a direct number. Direct numbers cost an extra $4.99/month unless you've included them in your initial contract.
Digital lines are what are attached to devices like deskphones and desktop apps that give them the ability to receive AND make calls. Every digital line comes with number. Deskphones must have digital lines to function, and desktop apps with digital lines with be able to make calls entirely through the RingCentral app. Line costs vary depending on the account.
Users can have multiple digital lines and direct numbers on their extension, but a call to any number on the user extension will ring everything.
I'm a bit confused with how you worded your question above though, so could you please clarify what exactly you're wanting in terms of setup?
~Matt

Right now all users have the mobile app loaded on the phone and i guess have "virtual extensions" (meaning 1 person = 1 user).  Although we use their extensions able to transfer calls TO them (within the app), rather than them using the app to make calls. 

It sounds like as long as a user is not using Ring Central to MAKE calls out - then there is no need to purchase a line or receiving outside calls to their extension, then we wouldn't see additional billing issues?    

However, when using Ring Central to replace having a separate company phone (as in my case and in another user's case) = we use Ring Central like we would use a business phone =- to make business calls -- and this is why we really need specific DIDs - as we would definitely exceed any outside incoming/outgoing minimum restrictions.

By mobile users without a digital line we do not mean only Mobile App users, but any mobile user, which would include a desktop app users. Desktop app users without a digital line making/receiving 10+ qualified calls in a month will be billed as a digital line. Inbound calls do count toward this 10 call limit. The main exceptions are:

 

• Missed calls and voicemail
• Calls that are forwarded on to digital lines
• A companys internal, extension to extension calls

Think of a line = a 10 digit phone number like you might have for your home or mobile phone.

An extension is usually 3 or 4 digit number with no telephone number directly associated to it.

Does that help?