Interesting coincidence that you are discussing how you used SDR-Console / SDRPlay to track RFI from DECT cordless phones.

For the first time - I did just that this week while helping a friend.

We are tracking 2 RFI sources:
(1) powerline source causing RFI on HF has been located &
(2) some (as yet) unknown source causing interference to his AT&T and Panasonic DECT phones.

These DECT phones operate in the 1.9 GHz range.  The exact frequencies were in the user manuals. 

In investigating this phone RFI problem, we used SDR-Console with an SDRPlay RSPDx.  It was very interesting to visualize the transmissions from the base unit and the handsets.
His phone RFI is interference TO HIS PHONE - - vs. Allan's RFI from a DECT phone.

I have tried other SDR software - but for RFI sleuthing, SDR-C is the best.  Its Signal History feature is most helpful. 

For anyone interested in locating and mitigating RFI sources, be sure to search archives of the RFI reflector:
http://lists.contesting.com/mailman/listinfo/rfi

Also, the ARRL's website has a very good RFI page:
http://www.arrl.org/radio-frequency-interference-rfi

Earlier this year, WD8DSB developed a small UNIDIRECTIONAL and BROADBANDED portable loop antenna for RFI hunting. It was the cover story in QST March, 2021.
To me, it seems like a breakthrough.
It pairs very well with SDR-Console, SDR receiver, and a laptop.

73, Alan K0AV