Forked/Active (SPANless) Recording using built-in bridges
Starting from version 6, CallReplay can record Cisco phones without using any kind of port mirroring on the switch. Only Cisco phones with built-in bridges can be recorded (like 7941 and newer).
More information. Version 8.0 introduced IPTrade active recording. Mitel MCDs are always actively recorded.
Passive network sniffing
CallReplay does not use any CTI ports to the PBX, which cost extra and may place additional load on the PBX. Instead, it uses passive network sniffing, which is completely undetectable and places zero load on the CM. Below is a call flow diagram in a internal network for recording external calls. Each call has 2 components, RTP (green) and Call Control (blue). The flow of each component is represented in the diagram. Note: Internal traffic (represented with red) will not be recorded unless CallReplay is plugged in the same switch as the phones to be recorded.
Hybrid CTI-SPAN recording
Added in version 7, CallReplay can record Cisco phones using JTAPI for the signalling and SPAN for the RTP of gateways. This is especially useful when recording old phones or devices without forked recording support, in complicated network environments.
