BT BIG Button + - Manual (Page 11)

BIG Button + ~ 4th Edition ~ 15th April ’02 ~ 4380
10
Please note you will require 2 x AAA batteries to benefit
from the BT Answer 1571/Call Minder message waiting
indication. These are not included.
Lift the battery cover and insert the batteries as shown.
1 Insert the batteries
Note
Batteries are only required if you want to use the 1571
feature.
You will still be able to make and receive calls via the
handset without batteries fitted. However, the message
waiting indicator will not function.