Hi,
To support a 7915 or 7916 Expansion Module, IP phones must have at least firmware 8-3-5 or a later version. The 7915 and 7916 Expansion Modules are supported only on the 7962, 7965, and 7975.
You need to install the firmware file for the 7915 expansion module with the following steps.
conf t
ephone X
type 79XX addon 1 7915
telephony-service
load 7915-12 B015-1-0-4.SBN <------ if you have 12 buttons expansion module ( 7915-12 B015-1-0-4.SBN is the load name )
or could be:
load 7915-24 B015-1-0-4.SBN <------ if you have 24 buttons expansion module.
no create cnf
create cnf
end
ephone X
reset
HTH
Manish