[Likely CGNAT issue with Virgin home internet] Inbound audio stopped working

[levgersh]

Hello,
My inbound audio stopped working.
People on the other side of the line can hear me but I cannot hear them.
This problem only started today March 12, 2026
I am using Grandstream HT801V2 adapter
Attempted reboot of ATA and Modem, did not help.
Please help

[Liptonbrisk]

1) Are you still using Freephoneline? If so, you posted in the wrong forum. The Freephoneline forum is located at viewforum.php?f=8

2) If you're still with Virgin ISP, visit viewtopic.php?p=82979 and viewtopic.php?t=20199. There's nothing anyone here can do for you since Virgin moved its customers to CG-NAT (carrier-grade NAT). You need a normal, unshared IPv4 IP address. Freephoneline and Fongo Home Phone don't currently support IPv6.

https://forum.virginplus.ca/t5/internet ... true#M1484

Hey Community,

Apologies on the delayed response, but wanted to ensure we provide a complete answer for everyone here who took the time to share and post on this topic.

Virgin Plus Internet services now operate behind CGNAT (Carrier Grade NAT). This means Virgin Plus Internet subscriptions receive a private IPv4 address on the WAN, which is translated to a shared public IPv4 address for outbound internet traffic.

With this transition, IPv4 features that require inbound connections—such as port forwarding and DMZ—will no longer function.

We understand this change may impact some Members’ existing network setups. We want to reassure all Virgin Plus Internet Members that standard internet connectivity and typical home usage will continue to work as expected with the default configuration.

For technical info, you can read through my responses in this thread: viewtopic.php?p=82837#p82837.

It may be possible in some cases to mitigate CG-NAT limitations by obtaining a public (relatively static) IPv4 address, using IPv6 end-to-end where available (and it's not currently with Fongo Home Phone and Freephoneline), or tunnelling traffic through a VPN or VPS that provides public IPv4 egress. One general example of working around CG-NAT using a VPS and WireGuard is here (not specific to Fongo Home Phone): https://www.reddit.com/r/unRAID/comment ... nat_using/.

Basically,
1. rent a VPS with a public IPv4 address,
2. install WireGuard on the VPS,
3. set up WireGuard at home on a router or server, and
4. configure policy routing or split tunnelling so that only the HT-801 ATA routes through the WireGuard tunnel.

Again, that's just an example and may not work.

VPN and VPS configurations add cost and operational complexity and may also introduce increased latency and jitter. I will not be supporting VPN or VPS tunnelling configurations here, as supporting tunnelling runs outside the scope of these user-to-user forums (as does supporting other products and services than those offered by Fongo). Also, if the tunnel drops, then so does your Fongo Home Phone (or Freephoneline) service. Consequently, it's much simpler to say Rogers 5G/w CG-NAT doesn't work with Fongo Home Phone and Freephoneline.

Personally, I try to avoid any internet service that forces CG-NAT upon me.

It's also much simpler for me to say that Virgin home internet users that were transitioned to CG-NAT are also most likely out of luck until Freephoneline and Fongo Home Phone supports IPv6. I can't find AAAA records for sip2.fongo.com (as an example), which is the same as voip4.freephoneline.ca (at the moment).

If at all possible, I would avoid using an ISP that employs CG-NAT (carrier-grade NAT). Rogers 5G home internet, which uses CG-NAT, doesn't work with Fongo Home Phone (so, trying to get to work with Freephoneline won't be easy either). Virgin Plus Internet is switching customers to CG-NAT. Some Telus home internet and telMAX internet customers are also on CG-NAT. Rogers Xfinity home internet customers are on CG-NAT unless the modem/router combo or gateway is in bridge mode.

If you're with Freephoneline and confirmed with your ISP's (Virgin's) technical support (not sure I trust average phone reps to know what CGNAT is) that you're not on CGNAT, you should follow the steps listed here: viewtopic.php?t=20539 (including trying voip4.freephoneline.ca:6060, but chances are trying those steps is a waste of time due to CGNAT).

Unfortunately, there's nothing else I can do (and I don't work for Fongo).