Tony_Wong I can not change another sip port which is unable to register after changed, only can use port 5060 for sip registration.
Fred28 To what other port number did you wish to change it to? IVM does seem to work only with the port 5060 for SIP(in case you were planning to use 5061). You might want to contact NCH Technical Support to confirm: https://www.nch.com.au/support/index.html