The document discusses CoreStor, an IP recording solution from Delma that can capture and record IP traffic, including VoIP packets. It describes various methods for capturing IP traffic, such as using span ports, port mirroring, conferencing, or custom gateways. CoreStor is designed to integrate seamlessly into existing systems and provide recording in a single chassis. It supports standard computer hardware and includes replay, administration, and analysis client software.

1. CoreStor IP Recording
Voice over IP is a whole new architecture which presents several unique
challenges and opportunities for recording solutions. The functional components
can distributed around IP networks that are unlike traditional PBX or switch
environments in that there may be no centralised point of capture of the audio
such as at the MDF (Main Distribution Frame) in traditional technology.
Nevertheless, single points of capture can be established using networking
devices. In any case capture is effected by targeting a specific series of IP
addresses across the network.
Delma specialises in IP telephony interfaces to a wide variety of the worlds PBX's
and voice switches, building world leading technology into recording systems.
Delma has developed a IP recording solution that can capture IP traffic of all
kinds and not simply VoIP packets. Needless to say voice traffic is the most
common requirement in IP recording.
The Solution
The CorStor IP recording solution fits seamlessly into the current product
portfolio and philosophies. Delma is able to provide one solution, including mixed
telephony, in one single chassis. In line with the leading digital interface
technology, Delma will also decode additional call data such as the called and
calling party numbers directly from the network, without the need for additional
CTI integration.
Configuration of the system is simple and effected by entry of the IP addresses
and ports which carry the data packets for capture. There are a variety of
methods used by switch manufacturers and recording vendors to ensure that the
packets of interest appear on network ports which will be monitored. These
include:-
• Span ports
• Port mirroring
• Conferencing or other dedicated connectors
• Custom gateways
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2. IP recording via a Span Port
Switch manufacturers often provide a Span Port which carries a clone of the
traffic being transmitted to and received from IP telephones. This port was
originally intended for maintenance and support purposes but was soon latched
onto by the recording community as a good place to capture IP traffic for
recording purposes.
As in all cases IP traffic is received in the recorder using a standard network
card connected to a network which includes the SPAN port. In an ideal situation
all IP addresses to be captured would be in a single VLAN which reduces the
work of the recorder when sifting through network traffic searching for the IP
packets of interest. When there is a requirement for remote offices to be
recorded at a central location, Remote Spanning may be used. The spanning
possibilities rely on the switch manufacturer and not all vendors will have the
same functionality. Please check the switch vendor for these spanning options.
IP recording via Port Mirroring
Very commonly all of the IP telephone extensions serviced by a PBX or IP switch
are connected to a multi-port network switch. Each extension occupies a single
network socket in the switch and each telephone has its own individual IP
address. It is not possible to target the individual ports on the network switch
and this is overcome by mirroring or cloning the IP traffic onto a series of ports
on the network switch which are dedicated to the recording activity. Thereafter
the process of recording using a standard Network Interface card in the recorder
is the same as before.
Care must be taken to ensure that network switches to be used will support Port
Mirroring
IP recording via Conferencing
Conferencing may be used in low volume recording operations. As with
traditional telephone conferencing, calls of interest may be conferenced to a
dedicated extension which is actually the IP Recorder rather than a telephone
handset. The recorder is configured to accept calls in the same way as a
conferenced phone. Thereafter the process of recording using a standard
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3. Network Interface card in the recorder is the same as before.
Recording at a conference port must be conducted carefully if the sense of
stereo calls is to be preserved. i.e. both the calling and called party are sent in a
single stream to the conference port. The recorder has to perform additional
analysis to discover the sending and receiving IP data.
IP recording via Custom Gateways
Custom Gateway are to all intents and purposes a combination of conferencing
and port-mirroring. A switch vendor will provide a gateway comprising of a
single or multiple IP ports. The packets of interest appear on these ports and
can be captured using a hub or mirrored on a network switch. Thereafter the
process of recording using a standard Network Interface card in the recorder is
the same as before.
Recording at a gateway must be conducted carefully if the sense of stereo calls
is to be preserved. i.e. both the calling and called party may sent in a single
stream to the gateway port. The recorder may have to perform additional
analysis to discover the sending and receiving IP data.
The IP recording solution is not able to record IP traffic when the IPSec (IP
Security Protocol) protocol or any other audio encryption is in use. When
recording such IP solutions, trunk side recording is one of the alternatives if
there is no access to the encryption scheme. CoreStor can be manipulated to
support encrypted schemes.
Recording Scenarios
In addition to recording traditional PBXs which support VoIP, call centres, dealer
boards or trunk lines, CoreStor is able to record calls over IP from any source
which handles packets in a supported protocol (H323, RTP, SIP etc). Designed
for reliability and adaptability, all CoreStor solutions are built upon open
standards technology and “off-the-shelf” hardware for simple maintenance,
integrations and expandability. There is no doubt that IP recording is an
essential element in the future of telephony.
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4. Licensing
IP Licensing is effected using license code entry into the configuration profile.
This profile contains the licenses for the number of lP channels. The CoreStor
software treats every IP channel as any other telephony channel.
Hardware Formats
CoreStor is a software recording solution and as such is designed to run on
standard computer hardware. The system is currently supplied to run on servers
of P4 processor or higher and running MicroSoft’s XP Professional or Windows
Server software.
Load balancing and high channel recording configurations can be achieved by
installation of the recording engine component (a standard “service” and the
replay and administration client on separate servers/PCs
Replay and Administration Client software
CoreStor has a full featured administration, replay and analysis client application
with the following features:-
• System configuration data manager
• System status displays
• System user and security profile management
• Access to system control of CoreStor services
• Archive configuration and operation
• Recording schedule configuration and operation
• Recording and monitoring node set-up and configuration
• Collection of recordings from other non CoreStor active nodes for
centralised storage under CoreStor
• Search, review, analysis and replay/reconstruction of stored calls
including optional Word Spotting and Voiceprint Analysis with speaker
identification.
• Multi-channel call review and replay to facilitate incident analysis
• Optional target tracking and mapping add-ons
Replay screen
showing multiple
channels
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5. Typical schematic
CoreStor is developed and distributed under license by:-
Delma MSS Ltd,
Newhouse Farm,
Northington,
Alresford,
Hampshire SO24 9UB
Tel: +44 1962 735859
Fax: +44 1962 735890
Email: info@delmamss.co.uk
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