Yealink 53W will not register

[potatohead]

As per the title, I am trying to connect a T53W to a 3CX standard cloud instance using remote connection - STUN from behind a natted internet connection.

I've jumped through the phone firmware upgrade hoops, to the latest 3CX version 96.86.0.72, and the phone has been factory-reset.

The phone is set to provision from the cloud instance and seems to retrieve the configuration correctly (the line key is setup as specified, and the time zone changes to my locale. I can log in to the phone's web ui and see apparently correct account details), but the phone will not register the account whatever I try.

On the 3cx pbx, the options tab is set to allow remote phone extensions to connect. There is no additional detail in the 3cx events log, and a pcap on the 3cx side shows packets going backwards and forwards between the pbx instance and the phone (all TLS packets, on 443. Nothing apparently on 5066, the selected phone SIP port?).

On the phone side, the screen says 'No Service' and the status->accounts moves from 'Registering' to 'Register failed' after a minute or two. Periodically the phone reboots. I have no issues connecting a softphone to the same account, so I reckon the basic config must be OK. I have a second T53W which behaves in the same way, so hardware issues seem unlikely.

I am at my wits end now, having spent days trying to get what I'd expect to be 'simple out of the box functionality' going. It's not like I'm a voip novice, either. Any advice would be most gratefully received. (PS. An SBC is not an option for my operating environment.)

Many thanks
PH

 

[CentrexJ]

Check that sip alg is off on the remote end.

 

[potatohead]

Awesome, that appears to have done the trick. Thank you SO much Jonathan!

Is there any work around for the requirement to disable SIP ALG - it's not something the end users will necessarily have control over?

 

[CentrexJ]

The work around is an SBC. That said there are newer models phones coming out that have the sbc built in. This will help by not needing separate device or expense. Watch the forum. When those phones release I’m sure 3CX will make a big announcement.

 

[potatohead]

Thanks again, Jonathan. What about the Yealkink VPN? Is that a reliable alternative. I'm thinking: install an openvpn server on a self-hosted 3CX instance and provision the phones as 'network local' bound to the VPN network interface? I have managed previously to get openvpn connections working ok on the Yealinks, but I'm not convinced the phones will wait for the vpn to come up prior to registration, or that the 3CX server will handle this network config correctly from a nat/routing point of view?
PH.

 

[SweetAction]

The YealinkVPN works fine in handling the registration. We do this (it's unsupported) fairly frequently.

Our OpenVPN server is not on the 3CX box though.
Phone provisioning is "local lan" via DNS (we push split brain dns servers via OpenVPN).
As far as 3CX is concerned, it's a phone on the local lan.

Bonus - phone passthrough port is also on VPN now (so remote workers have a automatic VPN). Or maybe not a bonus to you.

 

[JohnS_3CX]

The best solution we can suggest is to use a 3CX SBC, which effectively bridges the phones up to 3CX.
It was created for cases like the one you described.