SV 9100 hotel phone message buttons

[NiceRing]

My customer is saying that in some of the rooms in the hotel that the button at the bottom of the phone, the long one that flashes when there is a message is not working properly. They tell me that when the button is pushed, it should call the voicemail system, but it doesn't. I am working on getting more details on this, but does anyone know if this is a programmable user function, or is it a system program item? I looked in all of the 15-xx phone programs, and don't see this as an option. I looked in all the hotel features and can't find it either.
The room phones are Cetis phones, sorry, don't have the model number right now, they are pretty basic sets.
Any suggestions?
Thank you.

 

[belevedere]

Usually the individual phone has the programming in it. Most Hotel phones are SLT's with speed dials. Try removing the face plate and look for a programming button/switch.