I connected it to a DEI router and plugged in an analog cordless phone. It's a bit difficult to set up, but with the guide from the company Modulus, I managed it.

In case someone uses it through a mobile router, they should pay attention to the enabled Codecs.
I could receive calls, but I couldn't make them. Eventually, I was helped by Grandstream and once I changed the codecs, everything was fixed. I am attaching a photo with the correct order of the Codecs

It works perfectly. The setup should be done carefully following the provider's instructions. The countless options in the setup leave no room for error.

I have been using it smoothly for 4 months. Much more cost-effective solution than buying a VoIP device. I have connected it to the network with powerline and also installed the app to receive calls on my mobile.

It needs to be set up in order to work, just like all others of its kind. This requires advanced IT knowledge, which is supposed to be provided by the VOIP providers. This specific one has a good interface and allows for programming many details, but the countless options can confuse you. Its operational lights are user-friendly and provide good updates. Its cost is very competitive - it's easy to pay four times as much for the same thing. 4 stars because it's not plug and play (like all similar ones) and I don't know how long it will last.

Very good for creating an analog device in voip.
With instructions from your provider, the setup is easily done

Although not recommended for beginners, as it has complex settings, it performs well and provides solutions. It also appears to be of high quality and without disconnections.

I have it for three years.
I have tried it with both Cosmote voip and on my PBX. I never encountered any problems. It works perfectly and flawlessly.
Instructions for Greek dial tones can be found on the internet.

Finally, a way was found to get rid of the OTE router and have the amazing Asus back again. It was a bit difficult for me to set up and have the phone working again, but I managed. You will need to request the vobb codes from your provider if you want the phone to work.

I haven't had it for a long time but for now it seems good. As for the dial tones, I found the following guide to be much more informative (it's not for the same model but the settings are the same):

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I got it to get rid of the Cosmote router in my FTTH home. It works great, the configuration will serve most people, it just needs a little googling to make the dial tones sound like Greek: https://www.3amsystems.com/World_Tone_Database?q=Greece,Dial_tone