Subscriber Identity Module (SIM)

Subscriber Identity Module

A Subscriber Identity Module (SIM) is part of a removable smart card ICC (Integrated Circuit Card) also known as SIM Cards, for cellular telephony devices such as mobile computers and mobile cell phones. SIM cards securely store the service-subscriber key IMSI (International Mobile Subscriber Identitiy) used to identify a subscriber. The SIM card permit users to change phones by simply removing the SIM card from one mobile phone and inserting it into another mobile phone or broadband telephony device.

SIM cards are available in two standard sizes. The one is the size of a credit card dimentioning (85.60 mm × 53.98 mm x 0.76 mm) and the second most popular miniature-version has a width of 25 mm, a height of 15 mm, and a thickness of 0.76 mm. Most SIM cards are supplied as a full-sized card with the smaller card held in place by a plastic links and can be easily broken off to used in a phone that uses the smaller SIM.

The first SIM Card was made in 1991, with Munich smart card maker Giesecke and Devrient selling the first 300 SIM cards to Finnish wireless network operator Elisa Oyj (formerly Radiolinja).

What is Softphone

Softphone is a phone that allows you to talk using VoIP without necessarily having a physical phone set. It is a piece of software, or part of a VoIP software, that acts as an edge allowing you to dial numbers and bring out other phone functions using a screen (that of your computer or PDA) and your mouse, keyboard or keypad. Commonly, the interface resembles a phone with buttons in place of the keys, which you press using the mouse to dial. An example is the Skype Softphone. For speaking and listening, a headset and microphone be sufficient. You can also use an IP phone or handset.

What is Softphone

Softphone is a phone that allows you to talk using VoIP without necessarily having a physical phone set. It is a piece of software, or part of a VoIP software, that acts as an edge allowing you to dial numbers and bring out other phone functions using a screen (that of your computer or PDA) and your mouse, keyboard or keypad. Commonly, the interface resembles a phone with buttons in place of the keys, which you press using the mouse to dial. An example is the Skype Softphone. For speaking and listening, a headset and microphone be sufficient. You can also use an IP phone or handset.

H.323 Protocl

H.323 is a protocol standard for multimedia communications. H.323 was designed to support real-time transfer of audio and video data over packet networks. The standard involve several different protocols outside specific aspects of Internet telephony. The International Telecommunication Union (ITU-T) maintains H.323 and these related standards. Most voice over IP (VoIP) applications utilizes H.323.
H.323 supports call setup, rip down and forward/transfer. Architectural basics of a H.323 based system are Terminals, Multipoint Control Units (MCUs), Gateways, an optional Gatekeeper and Border Elements. Different functions of H.323 run over either TCP or UDP. H.323 competes with the newer Session Initialization Protocol (SIP) another established standard often found in VoIP systems. A key feature of H.323 is Quality of Service. H.323 Technology allows real-time prioritization and traffic management constraint to be placed on the “best effort” packet release system like TCP/IP over Ethernet.

Session Initiation Protocol

SIP, the session initiation protocol, is the IETF protocol for VOIP and other text and multimedia sessions, like instant messaging, video, online games and other services. SIP is very much like HTTP, the Web protocol, or SMTP. Messages consist of headers and a message body. SIP message bodies for phone calls are defined in SDP (Session description protocol)

SIP is a text-based protocol that uses UTF-8 encoding
SIP uses port 5060 both for UDP and TCP. SIP may use other transports

SIP offers all potentialities of the common Internet Telephony features like:

call or media transfer
call conference
call hold

Since SIP is a flexible protocol, it is possible to add more features and keep downward interoperability. SIP also does suffer from NAT or firewall restrictions. (Refer to NAT and VOIP). SIP can be regarded as the enabler protocol for telephony and voice over IP (VoIP) services. The following features of SIP play a major role in the enablement of IP telephony and VoIP:

Name Translation and User Location: Ensuring that the call reaches the called party wherever they are located. Carrying out any mapping of descriptive information to location information. Ensuring that details of the nature of the call (Session) are supported.
Feature Negotiation: This allows the group involved in a call (this may be a multi-party call) to agree on the features supported recognizing that not all the parties can support the same level of features.
Call Participant Management: During a call a participant can bring other users onto the call or cancel connections to other users. In addition, users could be transferred or placed on hold.
Call feature changes: A user should be able to change the call characteristics during the course of the call.
Media negotiation: The inherent SIP mechanisms that enable negotiation of the media used in a call, enable selection of the appropriate codec for establishing a call between the various devices. This way, less advanced devices can participate in the call, provided the appropriate codec is selected.

What is WiMax

WiMAX is a wireless digital communications system, also known as IEEE 802.16, that is intended for wireless "metropolitan area networks". WiMAX can provide broadband wireless access (BWA) up to 30 miles (50 km) for fixed stations, and 3 - 10 miles (5 - 15 km) for mobile stations. The WiFi 802.11 wireless local area network standard is limited in most cases to only 100 - 300 feet (30 - 100m). With WiMAX, WiFi-like data rates are easily supported, but the issue of interference is lessened. WiMAX operates on both licensed and non-licensed frequencies, providing a regulated environment and viable economic model for wireless carriers.WiMAX can be used for wireless networking in much the same way as the more common WiFi protocol. WiMAX is a second-generation protocol that allows for more efficient bandwidth use, interference avoidance, and is intended to allow higher data rates over longer distances.

NGN (Next Generation Networks)

Strong competition is expected in the information networking ground over the next 5-10 years. As the competition increases, it will be essential for companies to position themselves suitably to take gain of their core competencies and to practice for the emerging telecommunications environment. In this competitive environment, mergers, alliances, and the onslaught of new entrants into the market have service providers struggling to find pioneering ways to retain and/or attract the most lucrative subscribers. Today’s service providers are striving to differentiate themselves within this going up competitive landscape by searching for ways to brand and bundle new services, achieve operational cost reductions, and strategically position themselves in relation to their competition. As Figure 1 illustrate, the top 15% of today’s housing subscribers in the US are said to account for about 95% of carrier income, Thus, many service providers are looking to Next Generation Network (NGN) services as a means to attract and/or retain the most lucrative customers.