Early Media - Call from a VOIP system to a PSTN phone (Public Service Telephone Network)
Called Party starts the conversation before the call was answered
Early Media is used for compatibility with older Telephone systems, non-VOIP systems. Such as your phone service at home, from one of the many Bell’s, older PSTN (public switched telephone network) networks.
Without Early media enabled, If you were to place a call home from the office and the person answering the phone at home started talking right away, you will miss the beginning part of the conversation, the Voip phone will not have received the 200 OK from the PSTN to begin the RTP Media Stream (Audio) portion of the call.
Early Media allows for Ring tone, Busy tones, and other announcement’s to played even if the called party has not Answered the phone.