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Sufficient network bandwidth between the Collector and the Cisco UCM is required to support the necessary concurrent call recordings. This can be calculated using the following formula:

bandwidth = bitrate x channels

Where bitrate is the codec bitrate and channels is the number of concurrent channels to be recorded (times one for mono, or two for stereo).

Due to the small size and high frequency of RTP packets, it’s not possible to utilise the full potential bandwidth before the network becomes a bottleneck and packet loss ensues.

Where the Collector and Cisco UCM reside on separate network subnets, the Cisco UCM must be able to route to the Collector and the Collector must also be able to route to the Cisco UCM.

The following ports will need to be opened (globally, not for specific processes) on any firewalls between the Collector(s) and the Cisco switches:

To ensure security of data on-the-wire, Uniphore supports Secure SIP and Secure RTP (SRTP). SRTP keys are negotiated in the SDP using SDES (mechanism of negotiating security keys). We recommend using Secure SIP in conjunction with SRTP to keep the SRTP keys from being compromised.

To provide a secure SIP interface, TLS and DTLS are supported as SIP transports. The following protocol versions are supported. Previous insecure protocol versions are not supported.

SIPS URIs are supported, but not required with either TLS or DTLS transports.

The cipher suites (listed below) are supported in order of preference. On first start with either TLS or DTLS transports enabled, the Diffie-Hellman (DH) parameters are automatically generated. This only happens once on first start but takes several minutes to complete. The OpenSSL command line window must not be closed during this operation.

Secure RTP operates in three modes:

The following cipher suites are supported in order of preference.

The following SDES session parameters from RFC 4568 are supported. The far end may use them to override the session defaults. These overrides will be honoured by the Collector.

Secure RTCP

If SRTP is in use, Uniphore will also expect any RTCP to be secure (SRTCP). Receiver Reports transmitted will be secured using SRTCP and the negotiated keys.

To avoid recording silence (and therefore reduce storage requirements), the Collector can perform Voice Activity Detection (VAD) on received audio. VAD can use a combination of different signal analysis algorithms to identify voice. VAD is performed on each channel by analysing a 10-millisecond window. Each algorithm is performed on the audio within the window and a decision on whether that window contains voice or not is based on the levels falling within a set of configured thresholds.

Using the default configuration, it will take as little as 20-milliseconds of voice activity on a channel to trigger recording. Once voice activity is no longer detected, recording will continue for 5 seconds before ending. This prevents pauses in speech from causing excessive stopping and restarting of recording.

Enabling VAD does impact Collector performance and will reduce the maximum possible concurrent recordings. VAD is only supported with calls using the G.711 audio codec and cannot be performed on calls using SRTP.

The signal analysis algorithms currently used by VAD are:

ZCR is useful for distinguishing between tones and voice. Tones are often as loud as voice, but in general will be significantly higher frequency.

Integration testing of a basic interop between Cisco Unified Communications Manager V14, and Communication Recording Agent has been performed using Cisco 7861, 6941 and 7821 IP phones. For this integration any IP phone that supports Built in Bridge (BIB) is supported.