Cisco Exam Questions

Which of the following statements is most likely true?

You administer a small VoIP network. You have registered one Cisco IP phone with UCM. Every other IP phone
on the network is a thirdparty IP phone.
Which of the following statements is most likely true? (Select the best answer.)

A.
Only one H.323 endpoint is registered with UCM.

B.
Only one SCCP endpoint is registered with UCM.

C.
Only one SIP endpoint is registered with UCM.

D.
Only one MGCP endpoint is registered with UCM.

Explanation:
Most likely, only one Skinny Client Control Protocol (SCCP) endpoint is registered with Cisco Unified
Communications Manager (UCM) if you have registered one Cisco IP phone with UCM and every other IP
phone on the network is a thirdparty IP phone. By default, Cisco IP phones use SCCP, which is a Ciscoproprietary client/server call signaling protocol intended to be an alternative to H.323. A call signaling protocol is
responsible for the setup, maintenance, and teardown of a voice call. For example, call signaling protocols can
detect and report when a phone is offhook.
Although a few thirdparty IP phones support SCCP, Session Initiation Protocol (SIP) is more widely supported
on nonCisco IP phones. SIP is an Internet Engineering Task Force (IETF)standard call signaling protocol that is
supported by a wide variety of IP telephony vendors. SIP can be supported by Cisco IP phones with a firmware
replacement.
SIP uses a textbased signaling method, which is easier to understand and troubleshoot than the binary method
used by other protocols, such as SCCP and H.323. For example, SIP uses textbased INVITE requests and
ACK requests to invite a user to participate in a call and to acknowledge that user’s response to the INVITE,
respectively. Although SIP is typically used as a peertopeer call signaling protocol, it can also operate in client/
server mode. SIP is most commonly used by Internet telephony service providers (ITSPs). Therefore, many
nonCisco IP phones and video phones are SIP phones.
Neither Cisco IP phones nor thirdparty IP phones typically use H.323. H.323 is an International
Telecommunication Union (ITU)standard, peertopeer call signaling protocol. Peertopeer call signaling protocols
do not require a call processing platform, because the voice gateways provide their own call signaling and call
routing. Therefore, you would be more likely to register a nonCisco SIP IP phone than an H.323 IP phone with
UCM. Although UCM supports H.323, Cisco IP phones do not, because H.323 consumes a large amount of
processor and memory resources.
Neither Cisco IP phones nor thirdparty IP phones typically use Media Gateway Control Protocol (MGCP).
MGCP is a client/server call signaling protocol. MGCP is an IETFstandard protocol that can be used on some
Cisco IP phones with a firmware replacement.

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