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
voice over IP
Voice over Internet Protocol (VoIP), also called IP telephony, is a method and group of technologies for the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet. The terms Internet t ...
call traffic such as: reducing company vulnerability to lawsuits by maintaining recorded evidence, complying with
telephone call recording laws Telephone call recording laws refer to the official legislation regarding call recording in different countries, including how or if the consent of parties is required beforehand.
Australia
The federal ''Telecommunications (Interception and Acces ...
, 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.
Operation
By definition, Voice over IP is audio converted into digital packets and then converted to IP packets. VoIP recording is accomplished either by sniffing the network or by having the packets duplicated and directed to the recorder—passive recording or active recording, respectively.
* Sniffing (passive recording) is done by connecting to the
switched port analyzer (SPAN) port which allows the VoIP recording unit to monitor all network traffic and pick out only the VoIP traffic to record by either
MAC address
A media access control address (MAC address) is a unique identifier assigned to a network interface controller (NIC) for use as a network address in communications within a network segment. This use is common in most IEEE 802 networking tec ...
or by
IP address
An Internet Protocol address (IP address) is a numerical label such as that is connected to a computer network that uses the Internet Protocol for communication.. Updated by . An IP address serves two main functions: network interface ident ...
. 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. One can SPAN the VoIP Gateway port, giving 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.
* Duplication and redirection requires setting up a
VLAN
A virtual local area network (VLAN) is any broadcast domain that is partitioned and isolated in a computer network at the data link layer ( OSI layer 2).IEEE 802.1Q-2011, ''1.4 VLAN aims and benefits'' In this context, virtual, refers to a ph ...
and including 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
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.711
G.711 is a narrowband audio codec originally designed for use in telephony that provides toll-quality audio at 64 kbit/s. G.711 passes audio signals in the range of 300–3400 Hz and samples them at the rate of 8,000 samples per second ...
,
G.729a
G.729 is a royalty-free narrow-band vocoder-based audio data compression algorithm using a frame length of 10 milliseconds. It is officially described as ''Coding of speech at 8 kbit/s using code-excited linear prediction'' speech coding (CS-ACEL ...
/b and
G.723
G.723 is an 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 (ADPCM) to 24 and 40 kbit/s for digital circuit multiplication equip ...
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 approach offers some benefits over the long established method of sniffing (Passive) recording in environments where the handsets to be recorded are off site or in remote locations, or in situations where the network routing would mean that a passive solution would be overcomplicated. It also greatly simplifies recording internal calls, as it no longer necessary to duplicate the audio streamed between two handsets to the voice recorder as the telephony system will automatically manage this in any solution.
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
In computing, a firewall is a network security system that monitors and controls incoming and outgoing network traffic based on predetermined security rules. A firewall typically establishes a barrier between a trusted network and an untrusted n ...
technology to listen for VoIP calls on the LAN on a monitored port. The
RTP stream is then captured and converted to a
WAV
Waveform Audio File Format (WAVE, or WAV due to its filename extension; pronounced "wave") is an audio file format standard, developed by IBM and Microsoft, for storing an audio bitstream on PCs. It is the main format used on Microsoft Wind ...
file for storage and retrieval.
Other methods
VoIP calls can be recorded via
streaming audio
Streaming media is multimedia that is delivered and consumed in a continuous manner from a source, with little or no intermediate storage in network elements. ''Streaming'' refers to the delivery method of content, rather than the content it ...
recording applications. Most call centers and other organizations required to record calls would more often use a recording system offered by the
softphone
A softphone is a software program for making telephone calls over the Internet using a general purpose computer rather than dedicated hardware. The softphone can be installed on a piece of equipment such as a desktop, mobile device, or other comp ...
or
IP PBX
An IP PBX ("Internet Protocol private branch exchange") is a system that connects telephone extensions to the public switched telephone network (PSTN) and provides internal communication for a business. An IP PBX is a PBX system with IP connectivi ...
. Streaming audio recorders can be useful for home-based recording.
See also
*
Telephone tapping
Telephone tapping (also wire tapping or wiretapping in American English) is the monitoring of telephone and Internet-based conversations by a third party, often by covert means. The wire tap received its name because, historically, the monitorin ...
References
{{DEFAULTSORT:Voip Recording
Call-recording software
Voice over IP
Surveillance
Privacy of telecommunications
Communication software