said by Trimline:Really? WRONG!
Never open 5060, or port forward 5060 unless you want a lot of trouble (hackers). UDP ports 10001 - 20000 can be port forwarded without issue - these are used for RTP streams (voice). This can be forwarded depending on your situation. On example would be one-way audio.
Unless you are experiencing call audio issues, I would leave well enough alone.