VoIP recording
Encyclopedia
Voice over Internet Protocol (VoIP) recording is a subset of telephone recording or voice logging, first used by call centers and now being used by all types of businesses. There are many reasons for recording VoIP call traffic such as: reducing company vulnerability to lawsuits by maintaining recorded evidence, complying with laws, increasing security, employee training and performance reviews, enhancing employee control and alignment, verifying data, sharing data as well as customer satisfaction and enhancing call center agent morale .
(Switched Port ANalyzer) port which allows the VoIP recording unit to monitor all network traffic and pick out only the VoIP traffic to record. This is usually done by connecting an Ethernet cable being between the VoIP recording unit and the router, switch, or hub. Via the SPAN port, the recorder will "sniff" for signaling and RTP (Real Time Protocol) packets that have the identifying information contained in the headers of the packets is designated to record. There are two main ways to capture the RTP packets with the SPAN port. You can SPAN the VoIP Gateway port, giving you all the in/out bound traffic and offers one point of contact for recording. This is especially helpful in a campus with phones in multiple locations across the campus. However this method cannot capture internal, peer-to-peer (phone to phone) calls because their VoIP traffic is sent directly between the phones and doesn't flow through the gateway port. The other method is to set up a VLAN (Virtual LAN
) and include all the phones within the VLAN. Then SPAN that VLAN. This will allow recording all in/out bound traffic and internal traffic. The disadvantage is that not all phones at times are on a VLAN or the same VLAN, so multiple SPANS are needed. Another method is to use a concept called RSPAN (remote SPAN), in which the VLAN's that are set to SPAN are trunked across switches to a receiving switch.
, G.729a/b and G.723
and software only solutions as compared to the intensive hardware and software associated with legacy PBX recording.
Today, most of the VoIP vendors are offering VoIP recording methods specific to their VoIP call and communications management servers. These vendors are offering what is referred to as active VoIP recording where the recording vendor's solution becomes an "active" participant within the call for recording purposes. This offers a great deal of advantages for deploying VoIP phones and recording. Some of the advantages are the flexibility to record anywhere within the VoIP network, the ability to record encrypted calls and various recording methods such as record on demand, stop recording and save last call to name a few.
Disadvantages of "active" call recordings can include overheads on the PBX, the need for agent interaction and changes to the quality of the call. "Passive" call recording software
works by using packet filter technology to listen for VoIP calls on the LAN on a monitored port. The RTP
stream is then captured and converted to a WAV
file for storage and retrieval.
or IP PBX
. Streaming audio recorders can be useful for home based recording.
How VoIP recording works
Since VoIP calls travel digitally on computer networks rather than telecom cables, VoIP recording is done by tapping into the computer network rather than phone lines. Usually this is done by connecting to a router, switch, hub on the network, or through the PC attached to the VoIP phone. One way of doing this is by connecting to the SPANNetwork tap
A network tap is a hardware device which provides a way to access the data flowing across a computer network. In many cases, it is desirable for a third party to monitor the traffic between two points in the network. If the network between points A and B consists of a physical cable, a "network...
(Switched Port ANalyzer) port which allows the VoIP recording unit to monitor all network traffic and pick out only the VoIP traffic to record. This is usually done by connecting an Ethernet cable being between the VoIP recording unit and the router, switch, or hub. Via the SPAN port, the recorder will "sniff" for signaling and RTP (Real Time Protocol) packets that have the identifying information contained in the headers of the packets is designated to record. There are two main ways to capture the RTP packets with the SPAN port. You can SPAN the VoIP Gateway port, giving you all the in/out bound traffic and offers one point of contact for recording. This is especially helpful in a campus with phones in multiple locations across the campus. However this method cannot capture internal, peer-to-peer (phone to phone) calls because their VoIP traffic is sent directly between the phones and doesn't flow through the gateway port. The other method is to set up a VLAN (Virtual LAN
Virtual LAN
A virtual local area network, virtual LAN or VLAN, is a group of hosts with a common set of requirements that communicate as if they were attached to the same broadcast domain, regardless of their physical location...
) and include all the phones within the VLAN. Then SPAN that VLAN. This will allow recording all in/out bound traffic and internal traffic. The disadvantage is that not all phones at times are on a VLAN or the same VLAN, so multiple SPANS are needed. Another method is to use a concept called RSPAN (remote SPAN), in which the VLAN's that are set to SPAN are trunked across switches to a receiving switch.
Challenges of VoIP recording
VoIP is usually implemented as a cost saving measure over POTS (Plain old telephone systems). The same holds true now for VoIP recording. Most recording vendors are able to record the various standards of VoIP such as G.711G.711
G.711 is an ITU-T standard for audio companding. It is primarily used in telephony. The standard was released for usage in 1972. Its formal name is Pulse code modulation of voice frequencies. It is required standard in many technologies, for example in H.320 and H.323 specifications. It can also...
, G.729a/b and G.723
G.723
G.723 is a ITU-T standard speech codec using extensions of G.721 providing voice quality covering 300 Hz to 3400 Hz using Adaptive Differential Pulse Code Modulation to 24 and 40 kbit/s for digital circuit multiplication equipment applications...
and software only solutions as compared to the intensive hardware and software associated with legacy PBX recording.
Today, most of the VoIP vendors are offering VoIP recording methods specific to their VoIP call and communications management servers. These vendors are offering what is referred to as active VoIP recording where the recording vendor's solution becomes an "active" participant within the call for recording purposes. This offers a great deal of advantages for deploying VoIP phones and recording. Some of the advantages are the flexibility to record anywhere within the VoIP network, the ability to record encrypted calls and various recording methods such as record on demand, stop recording and save last call to name a few.
Disadvantages of "active" call recordings can include overheads on the PBX, the need for agent interaction and changes to the quality of the call. "Passive" call recording software
Call recording software
Call recording software records telephone conversations over PSTN or VoIP in a digital audio file format. Call recording is distinct from call logging and tracking, which record details about the call but not the conversation; however, software may include both recording and logging...
works by using packet filter technology to listen for VoIP calls on the LAN on a monitored port. The RTP
Real-time Transport Protocol
The Real-time Transport Protocol defines a standardized packet format for delivering audio and video over IP networks. RTP is used extensively in communication and entertainment systems that involve streaming media, such as telephony, video teleconference applications, television services and...
stream is then captured and converted to a WAV
WAV
Waveform Audio File Format , is a Microsoft and IBM audio file format standard for storing an audio bitstream on PCs...
file for storage and retrieval.
Other Methods of VoIP Recording
VoIP calls can be recorded via streaming audio recording applications. Most call centers and other organizations required to record calls would more often use a recording system offered by the softphoneSoftphone
A softphone is a software program for making telephone calls over the Internet using a general purpose computer, rather than using dedicated hardware. Often a softphone is designed to behave like a traditional telephone, sometimes appearing as an image of a phone, with a display panel and buttons...
or IP PBX
IP PBX
An IP PBX is a business telephone system designed to deliver voice or video over a data network and interoperate with the normal Public Switched Telephone Network ....
. Streaming audio recorders can be useful for home based recording.
See also
- Voice over IPVoice over IPVoice over Internet Protocol is a family of technologies, methodologies, communication protocols, and transmission techniques for the delivery of voice communications and multimedia sessions over Internet Protocol networks, such as the Internet...
- Telephone recording lawsTelephone recording lawsTelephone recording laws are laws that govern the civilian recording of telephone conversations by the participants ....
- Telephone tappingTelephone tappingTelephone tapping is the monitoring of telephone and Internet conversations by a third party, often by covert means. The wire tap received its name because, historically, the monitoring connection was an actual electrical tap on the telephone line...
- Call-recording software