The fact is, if you need more lines, you need more lines. 3CX does make accommodations for emergency calls. For example, even if a phone is not permitted to make outbound calls, 3CX will bypass any restrictions and place the emergency call.
But, let us be pragmatic for a moment. 3CX is in the business of selling phone systems based on the number of simultaneous calls NEEDED. In my view, you NEED more lines to ensure emergency calls can go out.
If you are concerned about paying for a rarely-used additional call path, perhaps you should look for a carrier that bills based on usage rather than "lines". Many carriers will let you make an unlimited number of simultaneous calls since their billing strategy is based on usage rather than the number of call paths.
Just curious, the only other option I can see is that the PBX choose a active phone call to drop so an emergency call can be placed (based on your argument that you only have 4 call paths). Which call do you suggest they drop? The longest running phone call? The shortest? A random phone call?
Frankly, 3CX practically gives away the phone system, so investing a tiny amount more to ensure emergency calls can go through is simply a no-brainer.
