It works now. THank you so much. Yesterday I did port forwarding

changed the RTP port range to 16800 to 16805 and no 5060-5061 and it didn't work. Today I change the range to 16800 to 16900, and added 5060 to 5061, the first time it didn't work either. I almost want to quit before the second try, and this time it works.

I was thinking the 5060-5061 is the key to make it work, but why? I always think after talking it already enter the RTP stage and no more SIP anymore.

Thank you sooo much for the kindness and patience.

Have a great holiday (Chinan National Day)!