IPA IP 2020 Question 77
A question IPA Japan published in 令和2年度 10月 ITパスポート試験 公開問題 問77, translated into English. ITPEC is based on the same exams.
Which of the following is an appropriate description concerning the technologies that are used in IP telephony?
Explanation
It can be built on a closed network such as a corporate LAN as well as on the Internet — IP telephony needs only an IP network.
IP telephony digitizes voice, splits it into IP packets and sends them over an IP network (VoIP, Voice over IP). Any IP network will do: the Internet, a carrier's closed IP-VPN, or a company's own LAN, where IP phones serve as extension phones. Through gateways, IP telephone services are also connected to the ordinary public telephone network.
Answer (a)
Why not others:
- •(b) — the technology that turns voice into IP packets is VoIP; an IP-VPN is a carrier's closed network that IP telephony can run over
- •(c) — IP telephone services connect to the public telephone network through gateways, so calls to ordinary fixed and mobile phones are possible
- •(d) — ISDN is a digital telephone line service; IP telephony runs over IP networks such as broadband Internet connections and needs no ISDN line
Key rule: VoIP packetizes voice, and IP telephony runs on any IP network, the Internet or a closed one, with gateways to the public telephone network.
Networks · AI-written, may contain errors
This question comes from the past questions IPA Japan publishes, translated into English by ITPEC Practice. ITPEC Practice is an independent study tool and is not affiliated with IPA or ITPEC. See the original paper (PDF) or Report an issue.