TOP 5 VOIP CONCEPTS TO KNOW FOR CCNA VOICEVoIP Basic for CCNA Voice ExamThe demand for IT professionals with a strong netw...
Voice Interfaces (Analog & Digital)Voice interfaces are what connect the voice device to the outside world. Whenimplementi...
There are two main voice digital interfaces, Basic Rate Interface (BRI) and PrimaryRate Interface (PRI). A BRI provides up...
G.729       CS-ACELP     Conjugate Structure Algebraic CELP 8-kbps                         (High Complexity)G.729A      CS...
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Top 5 voip concepts to know for ccna voice

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Top 5 voip concepts to know for ccna voice

  1. 1. TOP 5 VOIP CONCEPTS TO KNOW FOR CCNA VOICEVoIP Basic for CCNA Voice ExamThe demand for IT professionals with a strong network background in Voice andTelephony technologies is growing.Brief Info of CCNA Voice CertificationThe Cisco Certified Network Associate Voice (CCNA Voice) validates associate-levelknowledge and skills required to administer a voice network. The Cisco CCNA Voicecertification confirms that the required skill set for specialized job roles in voicetechnologies such as voice technologies administrator, voice engineer, and voicemanager. It validates skills in VoIP technologies such as IP PBX, IP telephony, handset,call control, and voicemail solutions.The CCNA Voice Certification assesses skills and knowledge related to the CiscoUnified Communications Manager 8.0 (CUCM) 8.0. It is typically employed by largeorganizations such as governments, large companies, and colleges. Additionally, theCCNA Voice Certification assesses skills and knowledge related to the CiscoCallManager Express (CME) and Cisco Unity Express (CUE) solutions typically used bymedium and small organizations such as companies with less than 2,000 employees,retail businesses, and small school districts.The implementation of Voice over IP (VoIP) has become more common as anorganizational alternative to traditional voice services. So here we talk about reviewsthe basic concepts of voice operations, and provides a base of knowledge fordeploying and operating these technologies.The CCNA Voice certification provides the candidate an associate level of knowledgein several common voice implementations. These implementations can includedevices like IP phones, gateways and gatekeepers, as well as voice concept basics likecall control and QoS. The CCNA Voice certification holder holds such titles as VoiceAdministrator, Voice Technician or Telecom Analyst, and has the ability to administerthese types of voice implementations.Sampling & Quantization (PCM)Sampling takes a continuous signal and converts it into a discrete signal; quantizationis then used to assign a value representing the sample. The amount of valuesavailable depends on the quantization type used; typically, in voice communications,8-bit quantization is used. The standard codec that is used on voice networks isG.711 which samples an 8-bit signal (via quantization) at 8000 times a second.Signals are digitally represented by 256 values from -127 (11111111) through 127(01111111) with the first digit representing value polarity. An example of this isshown in Figure 1. http://blog.router-switch.com/
  2. 2. Voice Interfaces (Analog & Digital)Voice interfaces are what connect the voice device to the outside world. Whenimplementing VoIP on modern equipment, it is still necessary in mostimplementations to utilize some type of voice interface even with the popularity ofVoIP compatible phones. There are two groups of voice interfaces that are used toconnect to other voice equipment, analog and digital.Analog Voice InterfacesThere are three major types of analog interface, these include:• Foreign Exchange Office (FXO)• Foreign Exchange Station (FXS)• Earth and Magneto (E&M)FXO and FXS interfaces are used in combination with one another. For example, astandard phone is a FXO device which connects to a FXS port on a voice device.Another example of this would be a FXS port on another telephone device whichconnects to a FXO port.The typical duty of an FXO interface is to provide on and off hook indication which isan indication of whether the analog loop is open or closed.The typical duty of an FXS interface is to provide battery current, ring voltage anddial-tone.E&M is an interface that is traditionally used to connect between voice switchdevices. There are five different types of E&M signaling, with Type 1 being the mostcommon in the U.S.Digital Voice Interfaces http://blog.router-switch.com/
  3. 3. There are two main voice digital interfaces, Basic Rate Interface (BRI) and PrimaryRate Interface (PRI). A BRI provides up to 2 channels of voice with a smaller signalingchannel. A PRI provides up to 23 channels of voice with an additional 24th channelwhich is used for signaling. Both of these interfaces are used more commonly invoice implementations as a replacement for an E&M analog interface. The use of BRIand PRI is also common when delivering voice to customer premises.Call Legs & Dial PeersA call leg is a commonly used term to reference a logical connection between twodevices. Depending on the number of devices that are used to connect a voiceconnection from source to destination, the number of call legs can get quite high.A dial peer on a Cisco device refers to a physical configuration of a call leg. There aredifferent dial peer types including a POTS dial peer and a Voice-network dial peer(commonly VoIP). Figure 2 shows a common example of dial peer implementation.CodecA codec is a process of coding and decoding a signal. Typically, a voice codec is usedto compress the voice signal into a specific bit-rate in order to be transferredbetween devices. The most commonly used codec is G.711 which is associated withuncompressed (mostly) voice. Table 1 shows a list of the most commonly usedmodern codecs.Codec Acronym Name Bit RateG.711 PCM Pulse Code Modulation 64-kbpsG.722 SB-ADPCM Sub-Band ADPCM 48, 56, 64-kbpsG.722.1 MLT Modulated Lapped Transform 24 and 32-kbpsG.722.2 ACELP Algebraic Code Excited Linear 6.60, 8.85, 12.65, Prediction Coder 14.25, 15.85, 18.25, 19.85, 23.05 or 23.85-kbpsG.723.1 ACELP Algebraic Code Excited Linear 5.3-kbps(5.3-kbps) Prediction CoderG.723.1 MP-MLQ Multi Pulse-Maximum Likelihood 6.3-kbps(6.3-kbps) QuantizationG.726 ADPCM Adaptive Differential Pulse Code 16, 24, 32 and 40-kbps ModulationG.728 LDCELP Low Delay Code Exited Linear 16-kbps Prediction http://blog.router-switch.com/
  4. 4. G.729 CS-ACELP Conjugate Structure Algebraic CELP 8-kbps (High Complexity)G.729A CS-ACELP Conjugate Structure Algebraic CELP 8-kbps Annex A Annex A (Lower Complexity then G.729) (Medium Complexity)G.729B CS-ACELP Conjugate Structure Algebraic CELP 8-kbps (G.729 with silence compression support) (High Complexity)G.729AB CS-ACELP Conjugate Structure Algebraic CELP 8-kbps (G.729 A with silence compression support) (Medium Complexity)Numbering PlanThe numbering plan is simply a plan that is followed in the allocation of phonenumbers. Most people are familiar with this assignment of various area codes andprefixes throughout the country. In North America, this plan is called the NorthAmerican Numbering Plan (NANP). This plan defines the use of a 10 digit phonenumber which includes a three digit Numbering Plan Area (NPA) that is used toidentify the area (also called the area code), the NXX that is used to identify thecentral office and a four digit station code which identifies the specific end device.The overview of voice operations covered in this article should help in understandingthe fundamental concepts that are part of a voice certification.---Original reading at Petri IT KnowledgebaseMore Related CCNA Voice Certification Tips:10 Things You Should Know About the Cisco CCNA Voice CertificationThe Benefits of Cisco VoIP http://blog.router-switch.com/

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