On a Electa Pro after you enable FNC 1 the speaker should work.Question is a a ICM call do you have to pick up the hand set to talk,I know you listen.

Are you talking about an NEC Electra Professional phone system???? If you are, I'll move this topic to the NEC forum.

Also, what model phone are you concerned about??

you will probably find headset is yes
which shuts off the speaker phone