CLCOR Voice Gateways And Session Border Controllers — 15 Questions

Question 1

A CUBE is rejecting calls because of a mismatch in supported DTMF methods. Which command forces CUBE to offer both RFC2833 and OOB DTMF?

Accepted Answer

dtmf-relay rtp-nte sip-notify. dtmf-relay rtp-nte digit-drop is a common configuration, but to support multiple, the dial-peer must explicitly define the relay types.

Answer

dtmf-relay all

Answer

dtmf-relay rfc2833

Answer

dtmf-relay h245-alphanumeric

Question 2

A CUBE is experiencing media cut-off issues after 30 seconds. Which parameter in the dial-peer configuration is the most likely cause if the re-invite is not being processed correctly?

Accepted Answer

session-timer. The timer-hold command controls how long the gateway waits for re-invites, but the issue is typically related to the session-timer which governs the SIP session refresh.

Answer

dtmf-relay

Answer

voice-class codec

Answer

timer connect

Question 3

You are configuring a dial-peer to route calls to a PSTN gateway using SIP. Which command is required to enable the use of the SIP protocol on the dial-peer?

Accepted Answer

session-protocol sip. The session-protocol sip command is the foundational command required to define the signaling protocol for a dial-peer.

Answer

session-protocol sipv2

Answer

signaling-protocol sip

Answer

voice-class protocol sip

Question 4

To allow a CUBE to handle calls for multiple tenants, which feature should be configured?

Accepted Answer

VRF. VRFs (Virtual Routing and Forwarding) are used in CUBE for multi-tenancy and network isolation.

Answer

Partitioned route patterns

Answer

Dial-peer groups

Answer

SIP headers

Answer

Voice class tenant

Question 5

You are migrating from H.323 to SIP. Which command on the gateway ensures that H.323 is disabled for new calls?

Accepted Answer

no h323-gateway. Removing the h323-gateway command or not defining h323 dial-peers prevents H.323 usage.

Answer

no signaling h323

Answer

disable h323

Answer

shutdown h323

Question 6

Which command displays the current status and statistics of all active calls on a Cisco voice gateway?

Accepted Answer

show call active voice. show voice call status provides a comprehensive list of active calls and their status.

Answer

debug calls

Answer

show call history

Answer

show voice status

Question 7

You are deploying CUBE and need to ensure secure media. Which protocol should you enable on the dial-peer?

Accepted Answer

secure rtp. SRTP (Secure Real-time Transport Protocol) is required for encrypted media, configured via secure rtp.

Answer

tls-srtp

Answer

encryption srtp

Answer

secure media

Question 8

Which THREE steps are required when configuring a new SIP trunk on a CUBE router?

Accepted Answer

Set session-protocol sip. SIP trunks require defining a dial-peer, the session target, and the session protocol.

Answer

Configure route group

Answer

Configure phone buttons

Question 9

What is the default dial-peer used if no other dial-peer matches a call on a Cisco IOS XE gateway?

Accepted Answer

Dial-peer 0. Dial-peer 0 is the system default dial-peer that acts as a catch-all if no specific match is found.

Answer

Dial-peer none

Answer

Dial-peer 1

Answer

Dial-peer 100

Question 10

You are deploying CUBE. Which command enables the CUBE functionality on the Cisco IOS XE router?

Accepted Answer

mode border-element. The mode border-element command is required under the voice service voip configuration to enable CUBE features.

Answer

enable cube

Answer

voice-service enable

Answer

service cube

Question 11

A Cisco IOS XE gateway is failing to route calls because the dial-peer is not matching the incoming call. Which command helps you identify the dial-peer that matched the incoming call?

Accepted Answer

debug voip dialpeer all. debug voip dialpeer all shows the matching logic for both inbound and outbound dial-peers.

Answer

show voice call status

Answer

show dial-peer voice summary

Answer

debug ccsip messages

Question 12

You are configuring CUBE for SIP-to-SIP header manipulation. You need to remove the Diversion header from outgoing INVITE requests. Which component is required to achieve this?

Accepted Answer

voice class sip-profiles. A SIP profile is required to match and modify or remove specific SIP headers in CUBE.

Answer

dial-peer voice

Answer

voice class codec

Answer

voice translation-rule

Question 13

When configuring CUBE for media flow-around, which command ensures the media goes directly between endpoints?

Accepted Answer

media flow-around. media flow-around prevents the CUBE from inserting itself into the media path.

Answer

media pass-through

Answer

media-bypass

Answer

media flow-through

Question 14

What is the primary function of a dial-peer destination-pattern?

Accepted Answer

To match the dialed number. The destination-pattern defines the number or pattern that triggers the selection of a specific dial-peer.

Answer

To define the codec

Answer

To specify the gateway IP

Answer

To enable SIP

Question 15

When troubleshooting CUBE SIP normalization, which tool allows you to view the normalized SIP messages in real-time?

Accepted Answer

debug ccsip messages. debug ccsip messages provides the view of the SIP signaling, including headers modified by normalization.

Answer

show voice class sip-profiles

Answer

debug voip ccapi inout

Answer

debug sip-ua

Answer

show sip-profile