Hi and welcome to JustAnswer,Thank you for the question and your patience. Should you still need assistance for information purposes only...Initially, is this a fresh/new install (in this location)? ...or has it been in use for some time (in the same location) and this issue just recent?
Is the symptom commonly exhibited when the handset is close to the base and when the handset is far from the base?
Have you tried re-locating the base unit even a meter or so away from its current position?
Any other devices near the base unit that may be causing electrical/radio interference? ...WiFi/routers, remote baby monitor, electronic lamps/dimmers, alarms and the likes?
Appreciate all these information.
Based on the above, then it would appear to be a hardware issue.
Would the Panasonic still be under warranty?
...or are you considering an internal DIY (do-it-yourself) repair approach?