In reply to a post by jchamier:

In reply to a post by einsteinagogo:

Route at this test site is a Ubiquiti UniFi USG-XG-8

I don't know Ubiquiti kit, but if it has a SIP ALG or any SIP support, disable it.

No issues with outbound, or inbound on either device if it registers last.

Other has said SIP ALG is not rwssponsible for this issue, and it's only Yealink VOIP phones which do not ring, and that's when behind other types of router.

and the changes made yesterday to Yealink phone, stopped working so it was random.

Not fixed.

In reply to a post by einsteinagogo:

No issues with outbound, or inbound on either device if it registers last.

So last register working... does to me sounds like a NAT issue or a ALG (Application Layer Gateway) interfering with the SIP INVITE packets being sent to your devices from the voiceless gateway server. Debugging this sort of thing through NAT is hard, which is why AA talk about using them as an ISP and using IPv6 as that ensures each device has a public IP and NAT clever tricks are not needed.

I use my VoIP mostly on my phone with Acrobits, and there is no way you can control what the mobile networks or third party WiFi networks do.

Do your devices support STUN ? (Simple Transfer of UDP through NAT); AA support this, and you'll see the same comment about SIP ALG on the support page:
https://support.aa.net.uk/VoIP_NAT

I have an old Cisco ATA which I no longer use, and my smartphone app. My parents have a Grandstream ATA and a DECT base station plugged in, and they have the same app on two different phones, and all ring at same time. My parents use Virgin Media's basic router/hub they provide, and I have an ASUS router with RMerlin firmware and any SIP turned off.

No knowledge of Ubiquiti kit.

In reply to a post by jchamier:

In reply to a post by einsteinagogo:

No issues with outbound, or inbound on either device if it registers last.

So last register working... does to me sounds like a NAT issue or a ALG (Application Layer Gateway) interfering with the SIP INVITE packets being sent to your devices from the voiceless gateway server. Debugging this sort of thing through NAT is hard, which is why AA talk about using them as an ISP and using IPv6 as that ensures each device has a public IP and NAT clever tricks are not needed.

I use my VoIP mostly on my phone with Acrobits, and there is no way you can control what the mobile networks or third party WiFi networks do.

Do your devices support STUN ? (Simple Transfer of UDP through NAT); AA support this, and you'll see the same comment about SIP ALG on the support page:
https://support.aa.net.uk/VoIP_NAT

I have an old Cisco ATA which I no longer use, and my smartphone app. My parents have a Grandstream ATA and a DECT base station plugged in, and they have the same app on two different phones, and all ring at same time. My parents use Virgin Media's basic router/hub they provide, and I have an ASUS router with RMerlin firmware and any SIP turned off.

No knowledge of Ubiquiti kit.

Again only happens on the Yealink units.

and used all 4 Yealinks unit, logged into AAISP, from four different seperate public IP addresses, different router equipment, and only the last device registered - WORKED.

I think I'm just going to reuse the N300 and register DECT handsets, (as other's on other Forums have also found)

https://support.yealink.com/document-detail/31e6527a...

thats the config page in the manual ....... nothing shown under advanced - i suspect stun is in there in advanced

Ok, if you use a Fritzbox then the FB registers with AAISP. When a call comes in, all VoIP phones behind the FB will ring (if configured accordingly). I am with AAISP and use a FB7590, have my smartphone registered and two DECT phones, but you could also register wired SIP phones. You can then set up so that all phones ring on incoming calls.