Phones stuck on speaker when picking up handset

[CK29]

I have a branch with 2 phones that when you pick up the handset the phone goes on speaker and they cant get off. they are not using headsets and they have checked the speaker button being stuck. Handsets have been replaced. Being 2 phones could this be a feature code entered for auto speaker that i dont know about?

 

[gberger]

Check under the phone, the handset is probably connected in the headset connector.

 

[Dasheen]

Could be the set is starting to fail. Move the set to a known working location and see if the problem follows the set.