Peer-to-peer calling in classic Hangouts
To improve audio and video quality, classic Hangouts audio/video calls use a direct peer-to-peer connection when possible. This allows classic Hangouts to connect your call directly to the person you're talking to, rather than routing the call through one of Google's servers.
When does classic Hangouts use peer-to-peer calling?
Every classic Hangouts call starts with all participants connecting to a Google server. The audio and video are then relayed to the people in the call. When there are only two participants in the call, classic Hangouts might attempt to establish a peer-to-peer connection between them.
If the peer-to-peer connection isn't possible, the Hangout will continue to send and receive audio and video using the existing connection to Google.
How does peer-to-peer calling help me?
Peer-to-peer connections improve almost all two-participant classic Hangouts calls. Routing audio and video through a Google server means that your call with a family member in the next town, or your colleague in the other building, could end up traveling farther than needed. Instead, a peer-to-peer connection allows the audio and video to be sent directly, allowing for the best possible quality.
Does classic Hangouts use peer-to-peer calling for a Hangout with more than two participants?
Peer-to-peer connections are used only for calls with two participants. If any additional participants join, classic Hangouts will immediately go back to sending and receiving data using the connection to the Google server.
How does peer-to-peer calling impact my personal information?
In order to create a peer-to-peer connection, it is necessary for Google to make the IP address of each participant available to the other. (The IP address is like a phone number; in order for the two devices to speak to each other, they need to know how to contact each other.) Though this happens in the background, it may be possible for a highly motivated and technically proficient person to discover the participants' IP addresses, which can be used to approximate location. This discovery can happen only during the call.
How does peer-to-peer calling work in an organization?
For organizations with internal networks, a peer-to-peer call where both parties are on the network would take place primarily within the network. If one participant is on the network and the other isn't, the IP address visible to the other participant is likely to be the IP address of the organization's gateway, rather than any specific internal network address (this depends on the individual network configuration). This is the same IP address that is displayed when a member of the organization visits a public website. From this perspective, classic Hangouts operates in the same way as most other Internet-enabled applications.