Trunk Recording vs. Station Recording
We were recently asked about which is preferred, trunk recording (record T1/E1 line) or station recording (digital or analog phone recording). Here’s our $0.02:
In most cases, station side recording is preferred. One key factor is that with trunk recording you are not able to record PBX calls. For example, if one employee calls another employee, that call does not cross your inbound / outbound trunks and cannot be recorded via trunk tap. With station-side recording, all internal calls can be recorded as well as other general inbound/outbound traffic.
With station-side recording it is also easier to segment the calls, especially if you do not have a computer-telephony integration (CTI) module active on your ACD/PBX (TSPAI, JTAPI, TAPI, etc.). The advantage in splitting the calls out is that a customer may call one department, and get transferred to another department. Since two agents are handling the call, and recordings are commonly used for quality monitoring on your agents, having two recordings is preferred so the agents can be evaluated independently, and so you can permission access to the recordings differently. You may not want a billing department supervisor to hear a tech support call and vice versa.
This kind of segmentation can be accommodated through a trunk-tap, but without CTI data this is done using SMDR information, which is not available until after the call has torn down and may not always be available in enough time for accurate use. This is especially true if SMDR is being used to trigger a recording start or stop and not just to update recordings with details like ANI, DNIS, agent extension, or queue description. Also, different switches may have limitation on how trunk channels are tracked and reported, making it difficult to match SMDR and even CTI data to recordings when a call has been transferred several times.
Most CTI-driven active integrations, such as Avaya DMCC (CMAPI), Nortel DMS, and Cisco JTAPI will behave like a station-side recorder. This is also the same with passive VoIP recording (packet sniffing). One exception is the ShoreTel TAPI/WAV integration, which behaves like a trunk recorder in the sense that is does not deliver audio for PBX calls; however you do have the ability to effectively separate recordings for each agent leg of the call.
Perhaps the biggest downside to station side recording is the wiring. Station side recording can be a passive tap /cross connect at the 110-or 66-block in your telecom wiring. Depending on what stations are to be recorded, you may also be able to do a split on a full amphenol cable between the PBX and the punch down blocks, which can be a cleaner wiring job.
