Yealink SIP-T48G Administrator's Manual page 535

Call recording enables users to record calls. It depends on support from a SIP server.
When the user presses the call record key, the IP phone sends a record request to the
server. IP phones themselves do not have memory to store the recording, what they can
do is to trigger the recording and indicate the recording status.
Normally, there are 2 main methods to trigger a recording on a certain server. We call
them record and URL record. Record is for the IP phone to send the server a SIP INFO
message containing a specific header. URL record is for the IP phone to send the server
an HTTP GET message containing a specific URL. The server processes these messages
and decides to start or stop a recording.
Note
It is not applicable to SIP-T19(P) E2 and CP860 IP phones.
Record
When a user presses a record key for the first time during a call, the IP phone sends a
SIP INFO message to the server with the specific header "Record: on", and then the
recording starts.
Example of a SIP INFO message:
Via: SIP/2.0/UDP 10.3.20.14:5060;branch=z9hG4bK1870385345
From: "1009" <sip:1009@10.2.1.48:5060>;tag=1385842459
To: <sip:1006@10.2.1.48:5060>;tag=2383911905
Call-ID: 0_1289812066@10.3.20.14
CSeq: 2 INFO
Contact: <sip:1009@10.3.20.14:5060>
Max-Forwards: 70
User-Agent: Yealink SIP-T23G 44.80.0.60
Record: on
Content-Length: 0
When the user presses the record key for the second time, the IP phone sends a SIP
INFO message to the server with the specific header "Record: off", and then the
recording stops.
Configuring Advanced Features
515