Phone Call Manager and Design - The Basics of design phones

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Business priority needs with the large companies today is to reduce the capital and support costs, while improving the effectiveness of their network infrastructure, security and management. Cisco IP telephony solutions that meet these requirements and provides a migration developed by PBX switches in a cost effective manner. PBX switches are both expensive to purchase and support. IP telephony offersAlternatives to the company PBX with Call Manager software that runs on a Windows server, replaced. The current version of Call Manager has features such as unified messaging integration, call routing with failover and migration easy to telecommunications infrastructure and ongoing management that is integrated with CiscoWorks.

From the Call Manager is designed to replace the phone system, there are all the telephony features you would expect in any other voice switches. It 'important to distinguishbetween IP telephony and Voice over IP, Voice over Frame Relay and Voice over ATM. The router voice interface module with the existing PBX at each site and do not use IP phones. IP telephony replaces the option PBX in every office with Call Manager for switching and routing all calls. In addition to the data lines are used to as Voice over IP Call Manager. This is an investment with the purchase of IP phones for use with Call Manager's workSoftware. How beautiful it is an inexpensive option called Softphone that runs as an application on the client desktop.

To consider the needs of employees to determine what is best for its employees. As mentioned above, there is diversity (failover) built-in IP telephony from a circuit, the routing of calls and the prospect IP phone. If the current PSTN circuit can fail over the IP WAN circuit can be used not available. The PSTN circuit is configuredTransport of voice traffic during periods when the circuit is overloaded or if WAN IP is not available. Call routing diversity with Call Manager clustering, a group of servers, processing continues to require, when a server is not available is called. The IP phone can be connected to another port such as desktop or campus switches can be connected to the same port and have separate VLANs, data and voice traffic. By connecting the phone to switch to other than the desktop onebe used to prevent both phone and non-availability of a campus switch should fail, however, is very expensive.

Quality of service is important, for every migration project voice from voice traffic is sensitive to delay. Bandwidth must be allocated to reduce or eliminate jitter. IP phones can prioritize voice traffic before it reaches the switch campuses. The campus switch examines each packet and bandwidth for packets that are designated as top prizePriority.

Project Example

This project uses Call Manager in an office with hundreds of employees. This implementation is the desktop phone and IP, the port of the switch itself, which is the least expensive option for connecting an IP phone network. There are three options for powering the IP phone. Some switches offer a campus in-line power module to power the phone. If the switch type is not available for your company, you can use the phone in a 120-pinV via an adapter or buying a skirt patch, which sends power on pins 1 and 4 of the RJ-45 phone.

Call Manager on a Windows server that is connected to the switch installed. A voice mail server with the server for Call Manager for processing requests associated with personal answering machine. Cisco offers a voice mail server called OOD. The switch connects the voice-enabled router 3660 with 100 Mbps Ethernet connection. The router running IOS Voice GatewaySoftware, the E.164 address resolution and offers WAN-Call Admission Control. There are two options available for the design of the circuit fail. The primary circuit will be used for the circuit data is with Voice over IP. The PSTN provider charges typically the customer through the use, it is important that your data with additional bandwidth for additional voice traffic. This address design requirements for performance while minimizing congestion andAfter the traffic on the PSTN.

As mentioned, the voice packets have priority for each IP phone, end-to-end quality of service at level 2 and 3 of the OSI model. Packet prioritization at Layer 2 has 3 bits in the field of 802.1p 802.1q tags. 802.1q is a day for each packet is appended with the VLAN membership of the package. If the package is sent via a local line switches, each switch will read the tags 802.1q VLAN membership for the determinationPackage.

6 that a higher priority features package from the default value of 5 - defined the 802.1p priority field of the 802.1Q specification for setting up these 3 bits for a value of 0 used. The switch examines the 802.1p priority field, and to packages with a number higher than those with fewer. Priority level 3, with 3 bits of the controlling differentiated services (DSCP) field of the type of service (ToS) byte, each with a specified IPHeader. 6 to favor a preference for voice packets show - These 3 bits are set to a value between 0.

Each IP phone must request an IP address, subnet mask and default gateway IP with DHCP services. There is also an option for items with static IP addressing, requires a configuration, when you assign the IP phone is implemented. The best way is DHCP, it is much less administrative overhead. The IP phone registers the IP addressand telephone number with the Call Manager before voice packets on the network. Cisco IP Phones are designed to use the G.729 voice compression for all traffic.

Once the traffic is compressed, sent to the campus is connected switch. When the switch comes, 802.1p and DSCP fields examined for prioritization. The voice packets are marked as a priority, then go through the campus before packets of data processed. Call Manager checks the numbers andforwards the packet with the correct routing information to the router. The router checks the DSCP field, because it is a Layer 3 device and give priority to voice packets before data packets for transport over the WAN. The call destination server manager controls the routing information packets and forward this item to change the campus, where it is connected to the IP phone.

Call Manager has both centralized and distributed models, which define defined in the Call ManagerThe servers are located throughout the enterprise network. The decentralized model is a manager in the office every call and calls are routed between servers in each office. The model can support 100 branches with 8 CallManager servers per cluster. Each office is helping 10,000 people per cluster. The centralized model has one or more of the Call Manager cluster at a particular office, all calls are sent to this office over the WAN for routing calls between the offices. A typical call Cluster Managementhas three servers with the central model, employees will handle 2,500 calls. And 'possible to implement additional cluster in the central office for scalability as the company grows.

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