Cisco Voice over IP (CVOICE)

VoIP Fundamentals (Considering VoIP Design Elements) Part 5

SIP T.38 Fax Relay Figure 2-12 illustrates a SIP T.38 relay operation. When the call control protocol is SIP, T.38 Annex D procedures are used for the changeover from VoIP to fax mode during a call. Figure 2-12 SIP T.38 Fax Relay Operation Initially, a normal VoIP call is established using SIP INVITE messages. The […]

Processing Voice Packets with Codecs and DSPs (Considering VoIP Design Elements) Part 1

Because WAN bandwidth is probably the most expensive component of an enterprise network, network administrators must know how to calculate the total bandwidth required for voice traffic and how to reduce overall bandwidth consumption. This section describes in detail codecs, DSPs, codec complexity, and the bandwidth requirements for VoIP calls. Several variables affecting total bandwidth […]

Processing Voice Packets with Codecs and DSPs (Considering VoIP Design Elements) Part 2

Effects of Voice Activity Detection on Bandwidth Statistically, an aggregate of 24 calls or more might contain 35 percent silence. With traditional telephony voice networks, all G.711 voice calls use 64 kbps fixed-bandwidth links regardless of how much of the conversation is speech and how much is silence. In Cisco VoIP networks, all conversations and […]

Processing Voice Packets with Codecs and DSPs (Considering VoIP Design Elements) Part 3

Configuring Codec Complexity On platforms that support the C549 DSP technology, the codec complexity is configured on the voice card (for example, the 2600/3600/VG-200 High Density Voice Network Module). Some platforms support only high complexity because they have enough DSPs onboard to support all T1/E1 channels that use the high complexity mode. To specify call […]

Processing Voice Packets with Codecs and DSPs (Considering VoIP Design Elements) Part 4

DSP Calculator For easier DSP calculation, a DSP calculator tool is available at the following URL (and requires appropriate login credentials for the Cisco website): http://www.cisco.com/cgi-bin/Support/DSP/dsp-calc.pl The following example shows how to calculate the required DSPs to deploy the following media resources on a single gateway: Router model: Cisco 2811 Cisco IOS release: 12.4(6)T Installed […]

Processing Voice Packets with Codecs and DSPs (Considering VoIP Design Elements) Part 5

Configuring Conferencing and Transcoding on Voice Gateways The configuration of transcoding and conferencing on a voice gateway involves DSP resource requirements, Skinny Client Control Protocol (SCCP) configuration, DSP farm and DSP farm profile configuration, and hardware configurations. The basic steps for configuring conferencing and transcoding on voice gateway routers are as follows: Step 1. Determine […]

Processing Voice Packets with Codecs and DSPs (Considering VoIP Design Elements) Part 6

Cisco IOS Configuration Commands for Enhanced Media Resources As previously demonstrated, you need to configure DSP-based media resources both on the hardware platform (for example, a Cisco IOS router) and on Cisco Unified Communications Manager. For reference, the following discussion details the Cisco IOS configuration commands for making router-based DSP resources available to Cisco Unified […]

Introducing Analog Voice Applications on Cisco IOS Routers (Routing Calls over Analog Voice Ports)

Voice gateways bridge the gap between the VoIP world and the traditional telephony world (for example, a private branch exchange [PBX], the public switched telephone network {PSTN], or an analog phone). Cisco voice gateways connect to traditional telephony devices via voice ports. This topic introduces basic configuration of analog and digital voice ports and demonstrates […]

Introducing Analog Voice Ports on Cisco IOS Routers (Routing Calls over Analog Voice Ports) Part 1

Connecting voice devices to a network infrastructure requires an in-depth understanding of the signaling and electrical characteristics specific to each type of interface. Improperly matched electrical components can cause echo and create poor audio quality. Configuring devices for international implementation requires knowledge of country-specific settings. This section examines analog voice ports, analog signaling, and configuration […]

Introducing Analog Voice Ports on Cisco IOS Routers (Routing Calls over Analog Voice Ports) Part 2

Analog Address Signaling The dialing phase allows the subscriber to enter a phone number (address) of a telephone at another location. The customer enters this number with either a rotary phone that generates pulses or a touch-tone (push-button) phone that generates tones. Table 3-2 shows the frequency tones generated by dual tone multifrequency (DTMF) dialing. […]

← Previous Entries

Next Entries →