Traditional Public-Switched Telephone Network (PSTN) telephone calls rely on a dedicated circuit between both phones. In contrast, Voice over Internet Protocol (VoIP) employs the same IP methods used to serve up Web pages to transmit voice data. Small data packets are passed from router to router on the network until they reach their destination, where they are reassembled into the complete digital file.
Basic VoIP components include:
Analog Telephone Adapter (ATA) - An analog-to-digital converter that connects normal phones to a computer or network. Used for residential VoIP and to enable companies to leverage their existing phones in VoIP environments.
IP Private Branch Exchange (IP PBX) - Routes internal voice traffic across the company's LAN or WAN-even to distant branch offices-and connects to a Telco's PTSN network for external calls.
Soft Phones - Software that allows users to make VoIP calls using a computer or handheld device.
IP Phones - Advanced phones that connect directly to IP networks via Ethernet cables.
The International Engineering Consortium offers an excellent tutorial on VoIP.
Cost benefits
Routing calls over data networks allows a company to avoid telephone toll and long-distance charges. And smaller companies can realize significant savings by switching their phone service to flat-rate or low-cost VoIP providers.
In addition, with both voice and data traffic running on the same network, there is only one network to manage and maintain. VoIP also allows more efficient telephone administration since admins can accomplish most phone moves, adds, and changes anywhere in the organization from a central interface.
Mobility
VoIP makes it easier to keep in contact with colleagues, customers, and others. You could, for example, plug your IP phone or soft phone in at home, on the road, or anywhere with a broadband connection using the same number. Someone could dial your local number and reach you in your hotel room in Hong Kong-with no added cost.
Next-generation features
In addition to the typical phone services, VoIP phones add several telephone features that increase productivity, collaboration, responsiveness, and customer service, including:
Universal in-box: Voicemail message files forward to the e-mail in-box.
Video phone/conference: Properly configured IP networks work much better than PTSN for real-time video.
Find me/follow me: Calls placed to a single number can ring at phones in several different locations (i.e. desk, cell, and home).
Presence: The ability to see if co-workers are available to take your call.
Enhanced caller ID: VoIP phones can link into CRM or Outlook data to automatically give the receiver additional caller information such as their order status, company, etc.
What's more, VoIP software lets users access these features through a graphical user interface instead hard-to-remember touchpad combinations.
Considerations
PTSN has always had one thing going for it: reliability. VoIP, however, is susceptible to the myriad threats, hiccups, and malfunctions inherent with any IP network.
Power: Unlike PTSN, VoIP phones require a power source. UPS backup is a wise phone-system safeguard.
Call quality: Latency, packet loss, and jitter that are imperceptible or acceptable with most data traffic can make VoIP calls unintelligible. A high-quality network and IP technology that gives priority to voice packets are keys to clear calls.
High-availably and security: With all communication and data traffic on the same network, the availability, security, and resiliency stakes are even higher.
Bandwidth: WANs and LANs require enough headroom to accommodate multiple simultaneous calls as well as the rest of the data traffic.
Proper network testing, analysis, and configuration are imperative for achieving high-quality, reliable business VoIP. HP IP Telephony Services can help any sized business plan, test, deploy, and maintain robust and secure VoIP environments
