Limiting RTP port range to 150 available ports

We are running asterisk in an evironment that limits the server to 150 external open ports. Has anyone had issues limiting the RTP port range to around 140 ports?

I know the calls will be limited by the available ports, 4 per call (2 from phone, 2 to sip provider), but will there be an issue with ports returning to the pool?

What does the user experience when all ports are in use on a new call?

Any tips to better managed the server with limited ports is appreciated.

Thank you