LTE5388-M804: SIP not able to register when in Cellular IP Passthrough (Bridge) mode.

TDiBOY Posts: 1
edited January 4 in Mobile Broadband

I have a requirement to have the external address hosted on the interface of the downstream firewall (behind the M804) to host services behind the firewall (not the NAT'd internal address).

When the M804 is in Router mode, I can made and receive calls using the voice function and associated SIP account on the unit (telephone attached to the phone port). When I change the Cellular mode to IP Passthrough, the SIP account is unable to register and I am unable to make or receive calls. I can't seem to find any setting that would need to be changed within the GUI to support this.

Is this a supported use case? If not, there needs to be some sort of warning that SIP will stop working once IP Passthrough is activated.

All Replies

  • Bob_C
    Bob_C Posts: 179  Zyxel Employee
    First Anniversary 10 Comments Friend Collector First Answer


    Conceptually, VoIP on the LTE5388-M804 only works under routing mode, it does not work in IP passthrough mode because the LTE5388-M804 already leases the WAN IP address (IP address from the ISP) to the LAN client, in your case it's a firewall.

    And in fact it seems to only work in routing mode too.



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