It's a Small World!
Until recently all telephones were analog. That is, the audio signal is completely processed via analog technology rather than digital.
Digital phones are frequently used in offices where the digital functions support voicemail and many other computer like operations in addition to the actual processing of the audio signal. They used in offices still receive an analog signal from the phone line, but process it and handle the other new functions digitally.
IBS Automation introduce “Grandstream”, a perfect IP telephony system for home, offices ..etc