Hi, please note that with version above C04 it support to change the NGN to IMS by changing protocol mode:
Set the current protocol mode.
Choose Advanced Configuration > Protocol Mode to display the protocol mode setting page.
Select SIP and click OK.
NOTE:
The IAD needs to be restarted if the protocol is switched. The configured data will be lost after switching; therefore, switch the protocol with caution. The protocol can be switched after about two minutes. You need to log in to the IAD again and configure data.