Hey there
I am part of a team creating a 90’s/00’s revival pop up store in Richmond early August, and the client has asked for an interactive telephone for the visitors.
The ask is to have the phone ring once when picked up then play a pre recorded message with clues. This will then reset once hung up waiting for the next person.
If someone out there has experience with Arduino/raspberry pi/telephone stuff who could help out with this please reach out. This will be a paid job for you 
Thanks
Alister