Phone tethering via USB

I have a Cisco SPA122 ATA connected to an ethernet port on my FTTC home netgear router and VOIP calls through Sipgate work fine.

For use at another location I am trying to set up a system using a different router, an ASUS RT-N66U, using a tethered mobile for internet connection using the same SPA122 for testing purposes.

I first of all set up the router for use with USB tethering. I thought setting this up might be challenging but in fact it was a doddle and my laptop connected via WiFi and ethernet to this USB setup wihout any issues.
But what did not work was the ATA as it just would not register with Sipgate despite being connected to internet and having been given a suitable IP address for the Asus router which uses a different network address to the Netgear.
Frustrated I plugged it back onto the home Netgear router and it quickly reconfigured with a new address and then registered immediately with Sipgate. Switching back to the Asus it remained obstinately unable to register.

Deciding a new approach was required I reconfigured the Asus for use as a repeater and changed the phone to Wifi Hotspot tethering. Using this mode everything including the ATA burst into life without any further action needed.

I know that I have found a solution but I would rather have it working via a USB cable as this will keep the phone charged up all the time.
Does anyone have any idea or suggestions why the ATA will not register when it is connected to the mobile by USB cable when other devices will plug into the ASUS ethernet ports and work normally in the same USB mode?

When you connect your laptop to the Asus RT-N66U with its USB connection to your mobile can you ping any internet site?

In reply to a post by Michael_Chare:

When you connect your laptop to the Asus RT-N66U with its USB connection to your mobile can you ping any internet site?

Yes that works. In fact I can connect laptop by wifi or ethernet to the internet in USB tethering mode. Its just the ATA that won't play ball even though it says it is online.

Possibly an issue with the Asus when it is configured as a router with a mobile broadband connection via the tethered phone.

In this setup, rather than the ATA, can you use a softphone VoIP client on the laptop (connected via WiFi to the Asus) to test your onward connection to Sipgate?

Ensure also you test using 10000, 10020 and 10005 for general audio, IVR/DTMF and echo test for full call functionality. You want to make sure you don’t have a one way audio issue for example even though it registers successfully.

Have you tried changing the SIP ALG setting on the Asus. Depending on how good or bad the device SIP stack and router ALG implementations are it may have to be disabled or enabled.

Post deleted by flippery

Snbforums.com search SPA112. may give answer in search results

In reply to a post by Pheasant:

Possibly an issue with the Asus when it is configured as a router with a mobile broadband connection via the tethered phone.

In this setup, rather than the ATA, can you use a softphone VoIP client on the laptop (connected via WiFi to the Asus) to test your onward connection to Sipgate?

Ensure also you test using 10000, 10020 and 10005 for general audio, IVR/DTMF and echo test for full call functionality. You want to make sure you don’t have a one way audio issue for example even though it registers successfully.

Yes I think it is probably the Asus in USB mode playing up as when I disconnect the USB cable and change the ASUS to repeater mode the ATA then immediately registers with Sipgate. Its what to do next to get USB mode to work that challenges......

In reply to a post by tdw42:

Have you tried changing the SIP ALG setting on the Asus. Depending on how good or bad the device SIP stack and router ALG implementations are it may have to be disabled or enabled.

This could be a good idea but I cannot find a mention of ALG in the router anywhere.

In reply to a post by jaba:

This could be a good idea but I cannot find a mention of ALG in the router anywhere.

My Asus RT-AX88U with Merlin firmware has the NAT helpers under "WAN" on the left menu, then "NAT Passthru" on the top bar, and then you have a list. I have a "SIP Passthrough" option with three choices:
* Disable = Actively block the port used by this protocol
* Enable = Allow NAT traffic through the protocol's port
* Enabled with NAT helper = Allow NAT traffic, and use a Netfilter module to help handle NAT forwarding for that protocol's traffic.

Mine is set to Disable and I use Acrobits Softphone on my iPhone over WiFi with a VoIP service from AAISP. So far not seen any problems... but I get very few calls.

Edited by jchamier (Thu 17-Feb-22 20:28:54)

In reply to a post by jaba:

In reply to a post by Pheasant:

Possibly an issue with the Asus when it is configured as a router with a mobile broadband connection via the tethered phone.

In this setup, rather than the ATA, can you use a softphone VoIP client on the laptop (connected via WiFi to the Asus) to test your onward connection to Sipgate?

Ensure also you test using 10000, 10020 and 10005 for general audio, IVR/DTMF and echo test for full call functionality. You want to make sure you don’t have a one way audio issue for example even though it registers successfully.

Yes I think it is probably the Asus in USB mode playing up as when I disconnect the USB cable and change the ASUS to repeater mode the ATA then immediately registers with Sipgate. Its what to do next to get USB mode to work that challenges......

You need to go through a logical process of elimination. Suggest as follows, when connected to the Asus when it’s got a tethered internet connection:

Can you check the debug or system log on the ATA?

This should give you a good idea of what could be going wrong and where to look next. Report back and we can go from there.

Here is what I did earlier today to get it working with my conclusions.

As I was getting nowhere with the USB problem it was time to go back to basics. I first set the router to just a single WAN to simplify things to check on the ASUS interface. Eventually I managed to get the registration light to come on but checking calls with 1000x resulted in no response.
During this I did some TBB speed checks which showed about 2Mbps if the test would start at all.

My 3g/4g connection here is weak downstairs where my office is. LTE discovery showed -107. But of course with wifi calling the mobiles work normally, independant of signal strength, and perhaps that is why the SPA122 was working when connected to the router in repeater mode.

I then took the all the equipment upstairs to the end of the house closest to the mast and signal strength was then much improved, -87. Resetting the router and phone back to USB mode resulted in immediate registration, Speed test showed about 14Mbps and I was able to use the verify 1000x codes successfully.
Thanks for all your help guys. I spent far too much time on this but got there in the end.

I am going to leave it upsairs running and connected for a few days just to reassure myself that it will be reliable when I take it over to instal in its intended location in France next month.

Great. Nice and simple in the end. Well done.

Edited by Pheasant (Fri 18-Feb-22 20:27:55)