Lots of ways to do it.
1. Create a call queue for your main line (and call it Main Line) add yourself to it and set the display settings to be the call queue name + called ID name or number. Redirect your main number to ring this line. Whenever someone calls it, you'll receive a visual identifier that says "MAIN LINE - Caller ID" on your phone. All direct calls will just show the clients caller ID, so you can distinguish main line and direct easily
2. Create another digital line called Main Line, direct your main calls to it, add it as a presence to your seat and turn on line monitoring. Anytime someone calls it, it will flash on the monitored line on your phone and you can press it to answer the call. This would likely be similar to what you had pre Ringcentral
