neilmurg wrote:The thought that a busy network would need to 'drop a call' to connect a new one is a bit misleading when it's not a point to point connection but discrete packets of data with gaps in between.
Um, yes and no.
If we take 2G, there are a discreet number of frequencies, each containing a number of time slots. Each timeslot will be one call (unless it uses half rate in which case it can be two calls...). Anyway, the air interface will be a finite number of available timeslots to use.
3G uses codes, and there are a finite number of codes for circuit switched calls, but there are lots.
4G doesn't have circuit switched calls, it's all data so it works as you suggest. You can make voice calls on it using VoLTE (Voice over LTE) but emergency calls aren't generally made over VoLTE as it doesn't have the integrity of a circuit switched call. If you make an emergency call when on 4G, you'll generally get a Circuit Switched Fall Back (CSFB) to 3G or 2G to make the call.
As for backhaul, it's still possible that on older networks that the calls will go through traditional digital exchanges with discreet (and limited) timeslots for each call.