Volume control over shared trunk lines in intercom systems

An intercom device comprising:

• a plurality of audio ports including a first port coupled to a first keypanel and a second port coupled to a trunk line providing a two-way audio connection between the intercom device and a second intercom device;
• a plurality of crosspoints for interconnecting the plurality of audio ports;
• a communication interface;
• and
• an electronic processor coupled to the plurality of crosspoints and the communication interface;
• wherein the electronic processor is configured to
• receive, from the first keypanel, a call request identifying a remote keypanel coupled to the second intercom device;
• transmit, to a trunk controller via the communication interface, a trunk request based on the call request;
• receive, from the trunk controller via the communication interface, a trunk setup message;
• activate a first crosspoint of the plurality of crosspoints based on the trunk setup message, the first crosspoint associated with the first port and the second port;
• apply a trunk gain value to the first crosspoint based on the remote keypanel;
• transmit, with an audio gain based on the trunk gain value, an audio stream received from the first keypanel to the second intercom device via the second port;
• receive, from the second intercom device, a gain adjustment value associated with the first keypanel and the remote keypanel;
• and
• apply an adjusted trunk gain value to the first crosspoint based on the gain adjustment value.