Are there any known good home phone systems for the Home Phone Connect

Question

I've had the Home Phone Connect now for several months.  I have had a Panasonic KX-TG7641 for a good while now.  I bought this system to connect a cell phone through the Bluetooth to make a receive calls at home.  This cell phone stayed docked in the charger next to the Panasonic base station.  There were a few extra steps involved in order to make calls using the Bluetooth and every time my mother-in-law visits it is an extensive training process to show her how to use the phone.  Every. Time. She. Makes. A. Call.
I saw the HPC and figured I could simplify the system and since the cell we kept connected was off contract, I got the HPC for free and signed up for 2 years with it. This was a mistake.  While I can always hear the callers on the line, they sometimes report that I am too garbled to understand.  Today I knew I was going to be on the phone on hold for a while, so I used my home phone handset for comfort (vice holding my Galaxy up to my head for an extended period of time)
After a 30 minute on-hold with the Veterans Administration I finally got through to an operator who informed me she could barely hear me/broken and garbled.  Where I have my HPC at it is right in a window and I have steady 2 bars on it always.  I told her I could call back on my cell phone, but she insisted we power through it so I wouldn't have to wait again on hold.  Well we eventually made it through the call. 
After hanging up I used my Google powers to see what the issue it/how to fix it.  It appears that the people that have issues when using the HPC also have Panasonic phones/base stations connected to it.       This might be because Panasonic phones are widely available and are the most common ones in use, but it might also be in that something is incompatible between the 2 systems.  Odd, since the way it connects is similar to an old POTS.  Could it have something to do with the DECT 6.0 that hey use (on the 1.9GHz band) where other older devices use standard 2.4 or 5.8?

Answer 1

Thank you for the tip.  Sorry if it's the wrong forum.  I don't post here often.  I searched for the Home Phone Connect under devices and found it under "Other" so figured this was the best place to post it.  Could you point me to the correct place for the HPC discussions? 
I'll double check later when I'm home on my computer to see iff the problems being reported are all using the DECT 6.0 (1.9GHz).  Might be causing some interference of some sort.