General Information and Main Benefit
VOIP or Voice over Internet Protocol (IP) is a telephony system that provides voice telephone calls over IP data networks. The main feature of this IP-based technology is that it sends conversations as data (or IP) packets over the Internet.
Currently, it is playing a vital role in replacing today’s (TDM-based) telephony infrastructure. This advanced telephony brings benefits to both consumers as well as enterprise (or commercial) customers. The main reason for migrating to VOIP is to reduce the (residential and commercial) voice communication cost. IPv6
Here are some applications that use VOIP technology and illustrate how they are revolutionizing the telecommunications industry:
Skype: A peer-to-peer (P2P) Internet technology with 220 million total user accounts (as in 2007)
IP PBX – A cost-effective business solution for enterprises to replace the POTS (Plain Old Telephone Systems) with full voice delivery capability (and thus saving money on trunking cost, for example)
IPv6 is documented in several RFCs (or request for comments) starting from RFC 2460. Although IPv6 is the successor of IPv4, both protocol versions will continue to be data-oriented protocols for the Internet in the coming years.
The other benefits of VOIP technology are mobility, unified messaging or presence-related communication function. For example, the users can use their Skype accounts from any computer (with speaker and headset) that is connected to the Internet. In its second generation, VOIP technology is now even starting to support roaming between Ethernet-based phones to cellular service.
Unified messaging (or UM) integrates different streams of messages (email, Fax, voice, video, etc.) into a single in-box, accessible from a variety of different devices. With the presence-related communication feature, users could see who is available for phone calls.
QoS issue for VoIP
At the present time, VOIP uses IPv4 that is a best-effort service and there exists no carrier-grade service level that we are all used to when using our regular phones (both at home and at work). Technically speaking, the current IPv4-based IP network does not have built-in QoS and, therefore, several quality (latency, jitter, echo) issues arise.
For example, quality of a voice-call can degrade significantly, if IP (voice) packets are lost or delayed at any point in the network between VoIP users. Users can also notice this quality degradation more in highly congested networks or over long distances. In order to address this quality issue, the next generation VOIP technology plans to use IPv6 that ensures QoS, a set of service requirements to deliver performance guarantee while transporting traffic (including voice) over the network.
How IPv6 Ensures QoS?
IPv6 implements QoS with the help classification and marking (of IP packets) to ensure a reliable VOIP infrastructure. With the help of classification and marking technique, the network can identify packets or traffic flows and then can assign certain parameters within the packet headers in order to group them. In order to implement QOS marking, IPv6 provides a traffic-class field (8 bits) in the IPv6 header. It also has a 20-bit flow label.
IPv6 Other current issues affecting VoIP
Exhaustion of address space is another issue as the momentum of VOIP grows significantly. The 32-bit address space in IPv4 precludes its scalability to a large user base. IPv6 addresses this problem of IPv4 with a very large address space that consists of 128 bits. Therefore, it is now possible to support 2^128 unique IP addresses, a substantial increase in number of computers that can be addressed with the help of IPv6 addressing scheme.
Also, in order for VOIP to be widely deployed, security concerns such as eavesdropping and hacking must be addressed as well. The other issues that impact VOIP: 1) End-to-end Integrity of signaling and bearer paths details 2) IP (voice) packet delivery across firewall and 3) NAT (network address translation) addressing issues that cause several networking problems (such as hiding multiple hosts behind pool of IP addresses) in end-to-end nature of the Internet and 4) Preventing denial or disruption of service.
P2P and Skype
Any discussion on VOIP is not complete if we dont talk about Skype. This extremely popular VOIP service uses P2P technology. Peer-to-peer technology allows communication between two computers that have similar capabilities.
When using the Internet, the important advantage is that the users dont need to any assistance from a third party network (e.g. assistance from servers as needed in server-client architecture) to establish communication. As mentioned in the Skype website A true P2P system, in our opinion, is one where all nodes in a network join together dynamically to participate in traffic routing-, processing- and bandwidth intensive tasks that would otherwise be handled by central servers.
Skype has revolutioned VoIP telephony because it offers very high-quality voice calls and the call betweeen two PCs users (with skype account) is free. The business impact of this is that carriers have been forced to reduce their long-distance calling charges to avoid losing market share. Skype is available on different OS platforms such as Windows, Mac OS X and Linux.