Private Messanger Signal – Authorizations?

RedPhone and TextSecure have been migrated to Signal, but I am a little worried about all the permissions required by the Signal application. Why does the signal require ex. location and schedule? I've tried searching for it, but I can not find any information about it.

Required permissions for Signal Private Messenger:

Device & App History // Identity // Calendar // Contacts // Location // SMS // Phone // Photos / Media / Files // Storage // Camera // Microphone // Wi-Fi Connection Information / / Device ID & call information // In addition to "Other" permissions.

Can any one explain why this application requires so much permission?