I have it connected to a Swisscom router via a Netgear managed switch and a Unifiswitch.
Plugged in and worked after I had to search for the default passwords on the internet to set a fixed IP...
Unfortunately the space is completely missing on outgoing calls....
I would check the pin colours on the RJ connector. For RJ10, red is on the far right. Compare with the pin colours on the working handset cable. I had the opposite problem. On my phone I need RJ10