When SIP-UA calls the called party through the proxy server, ____ .

• A.In addition to the external location request message, the calling UA other messages need not be forwarded through a proxy server
• B.to the not right
• C.Lord called UA All messages are forwarded through a proxy server
• D.In this environment, the called UA response message is sent instead of the main junction proxy called UA

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The CPE in the following options is ____ .

• A.DSLAM
• B.cable mode m
• C.machine top box
• D.access the server
• E.access into the switch
• F.Wide band router / modem

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A PBX of a company in Beijing was originally connected to the operator's telephone network through an analog line.In order to expand the capacity, it was proposed to apply for a digital line from the operator . ______ is the most economical choice.

• A.ATM
• B.E&M
• C.E1
• D.T1

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A session is initiated by a UA through a proxy server.When a UA wants to end the session,

• A.needs to be based on the proxy server is stateful or stateless session to decide which device to request
• B.will be the end of the session request is sent directly to the other UA
• C.will be the end of the session request is sent to the other party at the same time UA and proxy server
• D.will be the end of the session request to the proxy server

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The following are symmetric key algorithms

• A.AES
• B.RSA
• C.DSA
• D.DES

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