ChannelData Language was present in the proto, but was not accessible in the channel.go. Also missing ProtocolID #151
Description
I discovered this was missing and just submitted a Pull Request that contains code fixing this issue.
While fixing this, I also added support for the ProtocolID (protocol_id proto from Asterisk). Asterisk passes the protocol_id with the Channel. This is based on the underlying protocol. For chan_sip and PJSIP, this is the value of the SIP packet's Call-ID header.
Just submitted a Pull Request for both of these.