John wrote:

My Philips Kala cordless phone batteries need replacing. It is fitted
with 2 x AA 1.2v 600 mAh NiCd batteries and the handbook says only AA
600 mAh rechargeable batteries should be used as replacements. I have
some AA 2000mAh Ni-Mh batteries and was wondering if it would be ok to
use them in this phone?

I tried this with a BT Diverse phone (Siemens) which had the same dire
warning.

The batteries never stopped charging. I took them out when the phone got
almost too hot to hold.

I guess, if the batteries are just lying around then it's probably worth
a go.