Refer to the exhibit. An engineer is troubleshooting an issue where inbound calls to Cisco UCM with early media fail to establish. While investigating the issue, the engineer finds that Cisco UCM is s

The correct answer is A. voice-class sip rel1xx disable. The command 'voice-class sip rel1xx disable' disables reliable provisional responses (PRACK) on the CUBE dial-peer or globally. PRACK (defined in RFC 3262) is triggered by the '100rel' extension and is used to reliably acknowledge provisional responses (1xx) such as 180 Ringing.

Cisco Unified Border Element

Question

Refer to the exhibit. An engineer is troubleshooting an issue where inbound calls to Cisco UCM with early media fail to establish. While investigating the issue, the engineer finds that Cisco UCM is set to require a PRACK. But the Cisco Unified Border Element is not sending it. Which command is causing this issue?

Exhibit

Options

Avoice-class sip rel1xx disable
Bvoice-class sip early-media update block
Cvoice-class midcall-signaling block
Dvoice-class sip conn-reuse

How the community answered

(57 responses)

A
79% (45)
B
4% (2)
C
11% (6)
D
7% (4)

Explanation

The command 'voice-class sip rel1xx disable' disables reliable provisional responses (PRACK) on the CUBE dial-peer or globally. PRACK (defined in RFC 3262) is triggered by the '100rel' extension and is used to reliably acknowledge provisional responses (1xx) such as 180 Ringing. When CUCM requires PRACK (Require: 100rel) but CUBE has it disabled, CUBE will not send the PRACK acknowledgment, causing the call to fail. The fix is to remove this command or configure 'voice-class sip rel1xx supported' to allow PRACK.

Topics

#SIP Signaling#Cisco CUBE#Early Media#PRACK

Community Discussion

No community discussion yet for this question.

Full 300-815 Practice