The CallManager is a software-based call-processing system developed by Cisco Systems. It tracks all active VoIP network components; these include phones, gateways, conference bridges, transcoding resources, and voicemail boxes among others.
The Cisco CallManager Express system of voice and IP communications products and applications enables organizations to communicate more effectively-helping them to streamline business processes, reach the right resource the first time, and impact the top and bottom line.
We will first look at the dynamics and trends in the industry, and explain why IP Communications is becoming a compelling solution for small and medium businesses. Next, we will discuss the converged applications which are possible over an integrated voice and data network. We will then discuss the technical aspects of Cisco’s CallManager Express solution, explain some key features and review a few typical deployment scenarios.
The Cisco CallManager Express is the leading converged network telephony solution for organizations that want to increase productivity and reduce the costs associated with managing and maintaining separate voice and data networks. The flexibility and sophisticated functionality of the Cisco Unified IP network infrastructure provides the framework that permits rapid deployment of emerging applications such as desktop Cisco Unified IP Telephony, unified messaging, video telephony, desktop collaboration, enterprise application integration with IP phone displays, and collaborative IP contact centers. These applications enhance productivity and increase enterprise revenues.
What is Cisco CallManager Express?
CallManager Express is a cost-effective IP Communications solution for small
Businesses or branch offices. It is an optional IOS software license that extends the capabilities of the most popular Cisco Full Service Access Routers to simultaneously manage standard routing, VPN, IOS Firewall, and now local IP Communications.
Call processing is integrated within the IOS software to provide the core set of
Telephony features that customers require for their everyday business needs.
CallManager Express supports up to 120 users making it ideal for small businesses or branch office deployments. An intuitive, easy-to-use Graphical User Interface is included to set-up user preferences and facilitate system administration.
Quality of Service
Voice, as a class of IP network traffic, has strict requirements concerning packet loss, delay, and delay variation (also known as jitter). To meet these requirements for voice traffic, the Cisco Unified IP Telephony solution includes Quality of Service (QoS) features such as classification, queuing, traffic shaping, compressed Real-Time Transport Protocol (cRTP), and Transmission Control Protocol (TCP) header compression.
The QoS components of the Cisco Unified IP Telephony solution are provided through the rich IP traffic management, queueing, and shaping capabilities of the Cisco Unified IP network infrastructure. Key elements of this infrastructure that enable QoS for IP telephony include:
•Call admission control
•Compressed RTP (cRTP)
•Enhanced queuing services
•Link fragmentation and interleaving (LFI)
•Low-latency queuing (LLQ)
The Cisco CallManager Express addresses security in the following main areas, among others:
•Physical security for restricting physical access to important application servers and network components
•Network access security to prevent hostile logins or attacks
•Security measures for your Cisco router running Cisco Unified CME
•Mechanisms for defining calling privileges for various classes of users
•Careful network design and management to enhance security
The network infrastructure includes public switched telephone network (PSTN) gateways, analog phone support, and digital signal processor (DSP) farms. The infrastructure can support multiple client types such as hardware phones, software phones, and video devices. The infrastructure also includes the interfaces and features necessary to integrate legacy PBX, voicemail, and directory systems. Typical products used to build the infrastructure include Cisco voice gateways (nonrouting, routing, and integrated), Cisco IOS software and Catalyst switches, and Cisco routers.
Figure CCME Network InfrastructureC:\Users\Nirmal\Downloads\ccme1.jpg
In an CallManager Express-based IP Communications network, IP phones are connected to a voice-enabled Ethernet LAN switch, which is connected to an
CallManager Express-enabled router. The CallManager Express software on the Cisco router manages call processing, call control and feature control. This router also functions as a gateway to connect remote sites over either a private or public network, or to communicate with external callers.
In other words, IP-based Communications uses the same LAN as the data network. The Ethernet switch also provides inline power to the IP Phone. A desktop PC LAN connection can be connected in daisy-chain to the IP phone. In this way, one single cable from the switch takes care of power and network connectivity to the IP phone and the PC next to it, bringing significant cost savings.
The router with CallManager Express functionality acts as one single platform for Integrated Voice and Data. It leverages Cisco’s technology leadership in packet infrastructure and Voice-over-IP, to deliver high quality voice, and allows for simple deployment and management.
A network service is hosted on a computer network. These services are also known as service protocol since they help the users the in the network to achieve some functionality. These services are provided by servers that are on a Local area network to ensure user friendly operation and security. There are a lot of network services that are used in a network we will look at some of those services.
Domain Name System (DNS)
DNS enables the mapping of host names to IP addresses within a network or networks. DNS server(s) deployed within a network provide a database that maps hostnames to IP addresses. Devices on the network can query the DNS server and receive IP addresses for other devices in the network, thereby facilitating communication between network devices.
Relying on DNS, however, can be problematic. If the DNS server becomes unavailable and a network device is relying on that server to provide a hostname-to-IP-address mapping, communication can and will fail. For this reason, do not rely on DNS for communication between Cisco CME and the IP telephony endpoints.
Dynamic Host Configuration Protocol (DHCP)
DHCP is used by hosts on the network to get initial configuration information, including IP address, subnet mask, default gateway, and TFTP server. DHCP eases the administrative burden of manually configuring each host with an IP address and other configuration information. DHCP also provides automatic reconfiguration of network configuration when devices are moved between subnets. The configuration information is provided by a DHCP server located in the network, which responds to DHCP requests from DHCP-capable clients.
Trivial File Transfer Protocol (TFTP)
Within a Cisco Unified CME system, endpoints (such as IP phones running the SCCP protocol) rely on a TFTP-based process to acquire configuration information. The endpoints request a configuration file whose name is based on the requester's MAC. The configuration file includes the version of software that the phone must run and a list of Cisco Unified CME servers that the phone should register with.
If the configuration file instructs the phone to run a software file other than the one it currently uses, the phone will request the new version of software from the TFTP server. The phone goes through this process once per reboot of the phone or router, before registering.
Centralized call processing deployments require remote phones to download configuration files and phone software through the branch's WAN link. When scheduled maintenance involves the downloading of new software, download times are a function of the number of phones requiring upgrades, the file size, and the WAN link's bandwidth and traffic utilization.
Network Time Protocol (NTP)
NTP allows network devices to synchronize their clocks to a network time server or network-capable clock. NTP is critical for ensuring that all devices in a network have the same time. When troubleshooting or managing a telephony network, it is crucial to synchronize the time stamps within all error and security logs, traces, and system reports on devices throughout the network. This synchronization enables administrators to recreate network activities and behaviors based on a common timeline.
Standalone Network Infrastructure Overview
Cisco CallManager Express makes it a lot easier to manage a single site. It would require a lot of work to have maintained a standalone office before IP telephony since that office would require an onsite router which will be used only for data services and also needs a separate key system which will be used for voice services. Now the router can be made to provide an integrated and converged voice and data services to the standalone office. Though it has been converged it can be managed just like before by a VAR or SI or by an ISP. The advantages being both the service provider and business saving space, cost and management.
Cisco CME can be implemented in just wiring of a new office making it a lot more cost effective. Because the
Wireless LAN infrastructure
Connecting multiple cisco Callmanager exp systems
Integrating Cisco Unified CallManager Express with Cisco Unified CallManager
Integrating External Applications with Cisco Unified CallManager Express
Cisco Unified CallManager Express Security Best Practices
Managing and Monitoring Cisco Unified CallManager Express Systems