Audio guestbook

I have purchased a telephone (link below), wanting to turn it in to an audio guestbook (for weddings, birthdays etc). Imagine having it on the cake table or where gifts are left. A guest will lift up the phone, and it may say “Mr and Mrs smith cannot answer the phone right now, please leave us a message” or it may just be blank and go to ‘message bank’ immediately. The person would leave a message - no restraint on time. When they hang up it is saved as a message. Throughout the night people leave messages, the phone then gets sent back to HQ where all the files are taken off the device and saved to a usb or online site for the couple to listen to. I need to have the coding / device set up so it can be sent out to hirers and when it comes back I just need to download and re-set for it to head out again. Ideally there would be a few phones on the go - multiple colours / styles etc. We hired one for our wedding and it had its own battery back and terabyte attached so it could be placed anywhere in the venue. If you Google “at the beep” or “fete phone” these are companies who have this available. Link to the phone purchased: [login to view URL]