VOIP SIP custom port from WAN and LAN

  • Hi

    I would like to use a custom port for SIP registration, mainly to reduce the risk of being targeted from the WAN side.
    I defined a NAT rule and registration works ok from the wan.
    Softphone is set to use the custom port and NAT forwards it to 5060 on the local IPBX.

    Ideally, I would like the same softphone to register to the same custom port when connected to the LAN.

    Is NAT reflexion the way to go ?
    or is it better to change the server SIP port to the custom value ?
    (I would have to reconfigure the hardphones which were set up manually. No big deal if necessary).