Introduction to IP Telephony — Cisco Partner in Dubai

TechBee is one of the leading Cisco IP Telephony Partners in Dubai. IP telephony refers to communication services such as phone, fax, and voice-messaging that are delivered over a packet-switched IP network rather than a circuit-switched PSTN.

VoIP converts voice into IP packets and routes them to corresponding locations using voice-enabled routers. Users are typically unaware that VoIP has been implemented in the network; they continue to use their traditional phones, which are connected to a PBX. The PBX, on the other hand, is connected to a voice-enabled router that serves as an entrance point to VoIP rather than the PSTN or another PBX.

Traditional phones are replaced with IP phones, and PBXs are replaced with the Cisco Unified Communications Manager, a server for call control and signalling. Voice-to-IP conversion is handled by the IP phone itself, therefore voice-enabled routers aren’t required in the workplace network. If a link to the PSTN is necessary, a voice-enabled router or other gateway that forwards calls to the PSTN must be installed.

Converting an analogue speech signal into a digital format, then compressing and translating the digital signal into IP packets for transmission across an IP network, are the main processes in placing an IP telephone call. At the receiving end, the process is reversed.

The IP telephony architecture includes four distinct components: infrastructure, call processing, applications, and client devices.

Architecture Components at a Glance

End-to-end IP telephony: Using end-to-end IP telephony between sites that have previously established IP connectivity. IP telephony can be implemented as an add-on service to existing infrastructure.

Single-Site IP Telephony

Cisco Unified Communications Manager, IP telephones, LAN switches with inline power (PoE), applications such as voice mail, and a voice-enabled router are all part of a single-site IP telephony solution. The IP telephones are powered by the LAN switch via their Ethernet interface. Users can make external calls using gateway trunks that are connected to the PSTN.

Each site can be totally self-contained with single-site deployment. The PSTN is used to make all calls to the outside world and to remote areas. If an IP WAN is used in the single-site model, it is exclusively for data traffic and does not provide telephony services — so if an IP WAN fails or the WAN’s capacity is insufficient, call processing is not affected. The only external requirements are a PSTN carrier and PSTN network route diversity.

Best practice: use this strategy for a single campus or a facility with fewer than 30,000 lines.

Multisite WAN with Centralized Call Processing

Cisco Unified Communications Manager at the central site links to outlying locations over the IP WAN in a multisite WAN design model with centralised call processing. The centralised Cisco Unified Communications Manager handles call processing for remote IP telephones. The IP WAN transfers voice traffic between locations and calls control signalling between the central and remote sites. Voice mail and IVR systems are likewise consolidated, lowering the total cost of ownership and allowing for centralised management and maintenance.

The Enterprise Campus requires IP connectivity from the remote locations. Voice is converted into IP packets and sent to the local LAN through IP telephones, which are powered by a local LAN switch. The packets are forwarded to the right destination by the local router using its routing table. With Cisco Unified Survivable Remote Site Telephony (SRST) services, voice-enabled routers at remote sites can provide backup call processing functionality in the case of a WAN outage, extending high-availability IP telephony to branch offices.

The service provider must integrate QoS measures if a company demands high-quality voice communication over the WAN. A service level agreement (SLA) is a contract between a company and a service provider that ensures bandwidth and latency standards adequate for voice transfer.

Note: The routers have speech capabilities, allowing voice communication with the rest of the world via the PSTN.

Best practice: use this architecture for a main site with numerous smaller remote sites connected via a QoS-enabled WAN but not requiring full capabilities during a WAN outage.

Multisite WAN with Distributed Call Processing

A multisite WAN design architecture with distributed call processing consists of a number of separate sites, each with its own call processing agent, connected to an IP WAN that transports voice traffic between them. Because each site has its own call processing agent, the IP WAN in this approach doesn’t transmit call control signalling between the sites. In most cases, the PSTN acts as a backup connection between the sites in the event that the IP WAN connection breaks or has inadequate bandwidth for incremental calls.

Note: A standalone site is one that is solely connected to the PSTN and is not covered by the distributed call processing architecture.

Best practice: use this architecture for a big central site with more than 30,000 lines, or a deployment with more than six large sites (totaling more than 30,000 lines) interconnected via a QoS-enabled WAN.

Note: Cisco Unified Communications Manager Express, embedded in Cisco IOS software, enables call processing for up to 240 Cisco Unified IP phones — extending IP telephony to a small site or branch office with a low-cost, dependable, feature-rich solution.

TechBee designs and deploys Cisco Unified Communications Manager environments for businesses across Dubai, Abu Dhabi, Sharjah, Ajman, Ras Al Khaimah, Fujairah, and Umm Al Quwain. Whether you need a Cisco IP telephony partner in Dubai, a Cisco Unified Communications Manager Express installer in Abu Dhabi, or a multisite WAN voice design consultant in Sharjah, our engineers handle site surveys, QoS planning, and SRST configuration for branch resilience.

We also support UAE system integrators and enterprises migrating from legacy PBX systems to Cisco IP telephony, including PSTN gateway integration and Cisco MCS server deployment.