Create IVR with rasbperr PI

Use a raspberry PI 3 as a PBX/IVR 1) PBX system (FreePBX?) with SIP for google voice (& callcentric) 2) 1-3 extension to go to a rj11 jack (preferably 3 if possible) 3) 1 extension to send a signal from the pi to hardware specified by the dev to close a circut, only after entering code (for example when selecting extension 9, it should prompt for a password/code, & if the code is verified it should send a signal from a port) signal will go to door entry system & this will unlock the door 4) A few extensions that will forward the call (for John Doe press 2, & call will get transferred to cell/office)/ or to get transferred to voicemail 5) Access to listen to voicemail 6) (To be able to add message before the PBX extension list readout) (for example in urgent scenarios to be able to add message, so callers will know the info & won’t need to dial an extension)