题目
网络电话(Voice-over-IP,VoIP)是IP网上(1)(层)提供的一种业务,其目标是:以先进的网络技术、控制管理手段和编解码技术,以低于传统电话网PSTN的费用向用户提供话音服务。IP电话采用以IP包为单位的包交换,采用(2)(复用)传输,通常采用更先进的语音压缩编码,压缩后数码率为5.3~32kbit/s,信道利用率高。IP电话常用的信令技术包括ITU-T的(3)和IETF的(4)两套标准体系。
可选项:
A.应用层 B.传输层 C.网络层(IP层) D.网络接入层
E.DTMF复用 F.波分复用 G.异步时分复用 H.同步时分复用
I.OSPF协议 J.RIP协议 K.SIP协议 L.DTMF
M.H.323协议 N.H.324协议 O.H.264协议 P.H.265协议
第1题
Network managers have long(140)practical voice-over-IP(VOIP)solutions. VOIP(141)ease network management and decreases costs by converging a company's telephony and data infrastructures into one network. And a VOIP solution implemented at a company's head-quarters with far-reaching branch offices can(142)tremendous amounts of(143)in long distance phone bills, provided that solution delivers POTS-like voice(144)over the Internet.
A.await
B.awaited
C.awaiting
D.awaits
第2题
Network managers have long awaited practical voice-over-IP(VOIP)solutions. VOIP promises(71)network management and decreases costs by(72)a company's telephony and data infrastructures into one network. And a VOIP solution implemented at a company' s head -quarters with far -reaching branch offices can(73)tremendous amounts of(74)in long distance phone bills, provided that solution delivers POTS -like voice(75)over the Internet.
A.complicated
B.useful
C.ease
D.orderly
第3题
Network managers have long awaited practical voice-over-IP(VOIP)solutions. VOIP promises ease network management and decreases(66)by converging a company's telephony and data infrastructures into one network. And a VOIP solution implemented at a company's head-quarters with far-reaching branch offices can(67)tremendous amounts of money in long distance phone bills, provided that solution delivers POTS-like voice(68)over the Internet.
VOIP gateways are designed to convert voice from the(69)domain to the circuit switched domain. VOIP solutions use a digital signal processor(DSP)to process the voice data, preparing the voice sample for transmission by compressing voice and removing jitter. The VOIP equipment must comply with the(70)H.323 standard defined by the International Telecommunication Union, or ITU.
A.time
B.cash
C.costs
D.space
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