Below is the glossary of technical terms of protocols and network standards for reference purposes used in wireless communication, data communication, and telecommunication including meanings of ADSL, ACD, ATM - Codec, Gateway, Gatekeeper

ASYMMETRIC DIGITAL SUBSCRIBER LINE or ADSL is a method used to increase transmission speed of delivering data packets in a copper cable. Asymmetric Digital Subscriber Line facilitates division of the capacity with a high-speed channel to subscribers.  It is typically used for video data transmission and is a channel, which has a velocity significantly lower than the other direction.

AUTOMATIC CALL DISTRIBUTOR or ACD is a highly specialized telephonic system that handles incoming and outgoing calls. It recognizes and answers an incoming call, searches for the call’s database instructions on what to do with a specific call, plays phrases, records user responses, and sends over the call to an operator when a user becomes free or when the user finishes the phrase.

ATM or ASYNCHRONOUS TRANSFER MODE is a network switching technology, which uses 53 byte cells, which are useful for both, WAN, and LAN. ATM supports voice data and video data in real-time using the same infrastructure. Asynchronous Transfer Mode utilizes switches, which establish logical circuits between terminals that have easily scalable bandwidth and guarantee a good quality of service or QoS for transmission. In simple terms, unlike traditional telephone switches, which dedicate towards a dedicated circuit between the terminals, unused bandwidth in ATM-logic circuits can be utilized for other functions and uses.

CODEC, ALGORITHMS COMPRESSION/DECOMPRESSION are used for reducing the size of both multimedia data, i.e., audio and video. Compact encode is a multimedia data stream which is sent and then it is restored or decoded upon receiving.  If a user receives a data file or a call where the user is not able to hear anything, it is most likely that the application that user is using does not support codec with which data had been coded. Some of the most commonly used audio codecs are Global Standard for Mobile Communications or GSM, PCM, ADPCM, DSP TrueSpeech, CCITT and Lernout & Hauspie. Some of the most commonly used video codecs are Indeo, Cinepak, Video 1, and RLE.

GATEWAY is an element, which is in charge of making a bridge or filling a gap between the conventional telephone networks for example public switched telephone network or PSTN and the IP network. When a user tries to make an IP call with a traditional phone, someone somewhere down the line has to take care of converting analog signal into flow of IP packets and vice versa. This is just one of functions of gateway, which also provides a way through which a non IP device is able to communicate with other IP device on one end connected to a telephone exchange and on the other end to an IP network.

GATEKEEPER acts in combination with several other gateways and is responsible for performing works of bandwidth control, user authentication, and IP routing is considered to be the main brain of any IP telephony network but not all systems used by PSTIs are compatible (gatekeeper, gateway) apart. This is one of the main reason which has prevented IP telephony to spread more quickly. Currently this problem is being corrected and most of the systems including CISCO are based on H.323 protocols.