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DRAG DROP
Drag each phrase from the left, and place it in the appropriate column on the right. Phrases can be used more than once.
Explanation:
Internet telephony service providers (ITSPs) enable their customers to communicate with the outside world by connecting a Voice over IP (VoIP) network with the public switched telephone network (PSTN). Using an ITSP allows a business to reduce network management overhead and complexity by combining voice and data services on a single IP-based network. ITSPs enable companies with many locations to transmit voice and data to other branches over a single connection. Using a single network for both data and voice also allows network administrators to configure Quality of Service (QoS) features that can adjust the bandwidth available for data based on the bandwidth required for voice traffic. Because voice traffic is sent in real time, quality is critical.
Traditional PSTN connections require separate lines for voice and data. Telephony providers connecting to the PSTN require 64 Kbps of dedicated bandwidth for each voice line. Therefore, PSTN circuits are sold in blocks of 64-Kbps lines. Conversely, bandwidth from an ITSP can be purchased in only enough quantity to support the customer’s bandwidth requirements. In addition, the audio codecs and compression methods used by ITSPs for VoIP networks can reduce the amount of per-call bandwidth required and, therefore, support more simultaneous calls, ITSPs typically use Session Initiation Protocol (SIP) to connect VoIP calls, although some ITSPs use H.323. SIP is an Internet Engineering Task Force (IETF)>standard call signaling protocol. Although the text-based signaling used by SIP is easier to understand and troubleshoot than the signaling used by H.323, SIP uses more bandwidth than binary-based signaling methods like H.323 use. H.323 is an International Telecommunication Union (ITU)-standard, peer-to-peer call signaling protocol. H.323 requires more processor and memory resources than SIP.
The PSTN uses Signaling System 7 (SS7) to provide signaling for call setup and teardown. SS7 is a voice signaling protocol that is used worldwide on the PSTN. SS7 uses out-of-band signaling to perform call setup, maintenance, and teardown tasks. In addition, SS7 is responsible for routing calls through the PSTN and monitoring call statistics that can be used for billing purposes.
Using an ITSP can reduce costs per line for a business by providing lower-priced services that are similar to those provided by the PSTN, such as long distance. ITSPs route long-distance calls over the Internet, which reduces long-distance costs for the customer. VoIP networks can also handle more simultaneous calls to or from a single location with fewer physical lines.
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