NEC G355 User Manual page 17

Charge the battery of the I755 handset (either on its own or in the
handset) only in combination with either the:
I755 DECT Handset Desktop Charger and the Ten Pao
S008CM1200040 adapter that comes with the product;
I755 Charger Rack and the Ten Pao S040EM1200250 adapter
that comes with the Charger Rack.
Do not charge the batteries by any other means!
Plug the appropriate AC/DC adaptor in a wall outlet socket near the
equipment for easy access/removal of the AC/DC adaptor.
Important safety information
17