Echo On Cordless Panasonic Phones

[shivvy]

I have 2 cordless panosonic phones in the house. Recently people who phone say that they hear their own voice echoing when they call me. I can't think of anything that has changed recently e.g. Location of the base etc. that might be affecting them. It sounds ok from my end - the echo is only heard by the caller. I have looked online briefly but mainly see answers relating to an echo on the cordless phone, not the people who call.
Anyone got any advice?

[shivvy]

Can nobody help?!
I phoned my house earlier today and the echo is terrible!