More than a third of small business are using desktop IP phones today. If you want to join them, make sure you know your company’s answers to these seven key questions: 1. Is HD voice important? High-definition voice is clearer than older VoIP or landline calls, and has become a standard feature in business-class IP […]

Anytime we’re working on a VoIP deployment, we need to ensure the network is able to support the new application. In addition to obvious requirements including quality of service (QoS), power over Ethernet (PoE), and security planning, it may be advisable to do a bit of traffic engineering. The end product of the traffic engineering […]

Children’s Healthcare of Atlanta is ranked as the sixth leading pediatric hospital in the United States by Child Magazine. Double-digit growth over the past several years brought them to the point of needing a telecom system that would bring all of its phone numbers under a common area code and prefix, deliver consistent voice-mail, and […]

There are many interesting new issues that seem to have come with the addition of voice and video to the data network. Most of the engineers that are now working on VoIP networks come from either a pure data network background or a traditional phone system background. Each network offered certain issues that where common […]

Cisco IP phones support a variety of different audio codecs. In this post, I will explain some of the differences and explain which versions of CUCM and the Cisco IP phones support the various audio codecs. Audio codecs are responsible for sampling human speech (a sine waveform) and representing human speech on a communications network […]

For many years, the type of codecs developed for Voice over IP networks have been made with static sampling and transmission rates. For instance, G711a or u law, which is also known as PCM (pulse code modulation), has a sampling rate of 64 Kbps and will generate a fixed payload of 160 bytes every 20 milliseconds. This […]

Excerpted from the “VoIP Phone Hardening  —  Part 2” white paper. Download the complete paper from our Knowledge Center. Within Cisco implementation of Public Key Infrastructure (PKI) there are multiple PKI roots that each phone must trust. The phone keeps a list of all of the PKI roots that should be trusted called the Cisco Certificate Trust List (CTL). […]

This blog will discuss hybrid echo in voice over IP (VOIP) networks and how to hide the effects of echo in the network. Hybrid echo is caused by an impedance mismatch in the hybrid circuit when a two-wire analog phone connection meets a four-wire digital T1 trunk connection. A certain amount of echo is present […]

When integrating a Voice over IP (VoIP) system into an existing network it is very important to have a good understanding of how much bandwidth is utilized for each call on the network. For most people, just starting out the bandwidth calculations can be a very daunting task. But, with a basic understanding of the […]

IP telephony service providers (ITSP) offer a cheaper, efficient, and redundant PSTN call routing paradigm shift using voice over IP technology. This blog will investigate the Cisco Unified Border Element (CUBE) and the ITSP value proposition. Enterprises have been using T1 and E1 time division multiplexing (TDM) circuits to connect to the public switched telephone […]