This article gives a brief overview of Voice over IP (VoIP) for business from a fully independent view.
What is Voice over IP?
Voice over IP (VoIP) is a technology to transport digitized multimedia content over unreliable IP networks without guaranteed bandwidth or quality of service.
Other terms: IP telephony, Internet telephony, voice over broadband and a few others.
The technology was developed around 1995. The main difference between traditional telephony technology and Voice over IP (VoIP) is the kind of transport of real-time information (mainly voice, but also fax or video) through networks.
In pure analog telephony solutions the analog acoustic signal received at the microphone is converted to an analog electrical signal and continuously transferred over analog circuits to the destination. Here it is converted by a loudspeaker to an analog acoustic signal in the air.
In the Integrated Services Digital Network (ISDN) the analog signal generated from the microphone is converted to a continuous stream of digital bits by a signal processor with a specific chip set (codec). These bits are digitally transported from the digital end device through the whole network to the destination. At the far end the bit stream is converted back to an analog signal for output at the loudspeaker.
The main difference from ISDN to VoIP is the transport of bits through the network. In Voice over IP solutions the bits generated from the coder chip are collected and packed into data packets. The data packets are logical data units consisting of a data field (with the bits of the coder chip) and a control field with management information used in a packet switching network or at the destination. Each control field of a packet contains logical addresses of the source system and the destination system for identification and routing purposes. Maybe some additional information in the control field (the “packet header”) is used in the network or the receiver to know what to do with the packet or the data contained in the data field.
Each packet (composed of the header and the data field) is sent from the source IP telephone through the network to the destination IP telephone. At the destination the IP packet is unpacked; the data bits are forwarded to the decoder chip and converted to an analog signal for output at the loudspeaker.
Advantages of VoIP for Business
A shortlist of major advantages may include (examples):
- Voice over IP improves communication services far beyond voice and fax communication (e.g. instant messaging, ad-hoc video conferencing, video streaming, file sharing, presence service, social media integration, CRM integration, building automation integration, etc.).
- The technology allows vendor-independent integration of different standards-based VoIP solutions, what makes it future-proof.
- The flexibility of certain solutions offers the choice of different end devices like IP phones of different vendors. The support of mobile workforce allows flexible integration of mobile devices like smartphones or tablet computers as the new IP phones.
- The integration of external and internal partners into a personal communications environment accelerates project delivery or business processes.
- The use of Voice over IP technology lowers the Total Cost of Ownership (TCO).
- Provider access may be simlified and redundant without additional expenses.
- The offered large variety of solutions (on-premises, hosted, cloud, mobile) offers a big choice.
- The effort for adds / moves / changes / deletes can be reduced.
- Flexibility and cost cut for workplace may be increased.
- VoIP solutions may be integrated into corporate IT security services increasing security for telephony, fax and video services.
- Integrated management of VoIP and and IT services lowers the overall management costs.
Major challenges may be (examples):
- VoIP projects are much more complex than ISDN projects
- Dependencies of IT services are critical for project success and service availability
- Cabling and network infrastructure are the base for high quality communications services. Weak points lead to dissatisfied customers and interrupted business processes
- Availability of products and services are not guaranteed for different locations
- Separated infrastructure for VoIP and IT increases cost
- Ignored security concerns open doors for attackers
Standardization of VoIP Protocols
Standardization is very important for open and future-proof solutions. Different organizations developed and are still developing recommendations or standards for interfaces and protocols. The most important ones for Voice over IP are the International Telecommunications Union (ITU) and the Internet Engineering Task Force (IETF). The standards describe protocols for signalling and other purposes used in the Internet (Request For Comments, RFC). ITU describes an architecture named ITU-T H.323 for Voice over IP communication with main focus on provider services.
IETF supports a protocol called Session Initiation Protocol (SIP), RFC 3261, with main focus on multimedia communication over IP networks (e.g. the Internet).
Note: providers support SIP in their public Voice over IP services.
Vendors may follow their own standardization strategy and specify their own protocols. The reasons are manifold. Perhaps one goal is to implement features and functions not covered or supported in vendor independent standards. Another goal may be to build closed solutions to offer the best support to their customers.
Examples of protocols specified by certain vendors are: Alcatel Business Communications (Alcatel-Lucent), InterAsterisk eXchange (Digium), Jingle (Google, XMPP Standards Foundation), Meridian Customer Defined Network (Nortel), Skinny Client Control Protocol (Cisco) and many others.
Any questions or suggestions? Please leave me your comment.
Books and Seminars
Booklet “From ISDN to SIP”
Courseware “Voice over IP – Chances, Changes, Challenges”
About the Autor
Ronald Schlager is independent trainer, consultant, author and blogger with main emphasis on communications technologies and their applications.