DECT is the PITS

I want to put it on record that, with the possible exception of printer settings in the 1980s, the DECT menu system is the worst ergonomic system in the history of technology.
The Partridge office needs a speaker phone urgently, for reasons I will come to anon. The Philips cordless phone system I bought a few years ago because it was cheap has always irritated me with the commands that mean nothing, the impenetrable menu and its infuriating air of 'this is European Design at its best' smugness that I find completely insufferable. And, of course, one of the reasons it was cheap was that it has no speakerphone.
And if you have to use an insufferable machine all day, every day it gets to you.
I tried using VoIP with a microphone and speakers. What a crock. Whether this is because of the appalling broadband service in this part of the world (BT, this means YOU) or the dreadful and now deservedly defunct BT Softphone system or Skype being crap I'm not sure, but whatever the root cause I can't get an interview to come out of my computer speakers without clipping either my words or my interviewee's. Most of my interviews these days consist mainly of me apologizing for the glitches and promising to ring back immediately 'on a real phone'.
So finally I bit the bullet, went to Tesco and bought a BT Graphite GAP-compatible handset with speakerphone capability. 20 notes and worth 15 at the most.
Then I tried registering it to the Philips base station. What a nightmare. Nothing seemed to work. I tried pressing every single button quickly, slowly, quick quick slow but nothing.
Still the BT handset said 'NO LINE'.
In desperation I tried pressing the green handset and I got a dial tone! It was connected anyway!
It still says 'NO LINE' and it still connects. The speakerphone works brilliantly. But every time I answer a call, I will get a tiny buzz of rage as if from a miniature tazer in my brain, when I read the words 'NO LINE' and the call nevertheless instantly connects.