Which statement describes DTMF processing on Cisco Unified Contact Center Express with supported SIP-based agent IP phones that are registered to Cisco Unified Communications Manager?
Unified CCX CTI ports are notified of caller-entered digits (DTMF input) via JTAPI messages from Unified CM.
Unified CCX does not support any mechanism to detect in-band DTMF digits where DTMF digits are sent with voice packets.
In deployments with voice gateways or SIP phones that only support in-band DTMF or are configured to use in-band DTMF, an MTP resource must be invoked by Unified CM to convert the in-band DTMF signaling so that Unified CM can notify Unified CCX of the caller-entered digits.
Be sure to enable out-of-band DTMF signaling when configuring voice gateways in order to avoid using the previous MTP resources.
References: http://www.cisco.com/en/US/docs/voice_ip_comm/cust_contact/contact_center/crs/express_9_02/design/guide/UCCX_BK_C39FDB35_00_cisco- unified-contact-center-express_chapter_010.html.
When a call is made from an agent using a SIP-based IP phone that is registered to Cisco Unified Communications Manager (CUCM), the Cisco Unified Contact Center Express (CCX) platform needs to process the DTMF (Dual-Tone Multi-Frequency) digits that are entered during the call. DTMF is the tone generated when a caller presses a button on their phone's keypad, and it is used to transmit the caller's input to the receiving system.
There are several ways in which CCX can receive the DTMF digits. Let's review each answer option in turn:
A. Cisco Unified CCX receives the DTMF digits via SIP NOTIFY messages. This statement is incorrect. SIP NOTIFY messages are used to send event notifications between SIP devices, but they are not typically used to transmit DTMF digits.
B. Cisco Unified CCX receives the DTMF digits in the RTP payload based on RFC 2833. This statement is correct. RFC 2833 defines a standard method for transmitting DTMF digits in the RTP (Real-time Transport Protocol) payload. This method allows DTMF digits to be sent in a separate RTP stream from the audio stream, which makes it easier for CCX to process them.
C. Cisco Unified CCX receives the DTMF digits via JTAPI messages. This statement is incorrect. JTAPI (Java Telephony API) is a programming interface used to develop telephony applications, but it is not used to transmit DTMF digits.
D. Cisco Unified CCX receives the DTMF digits via SIP INFO messages. This statement is incorrect. SIP INFO messages are used to send out-of-band information during a call, but they are not typically used to transmit DTMF digits.
E. Cisco Unified CCX receives the DTMF digits as part of the audio encoding in the RTP stream. This statement is incorrect. While it is technically possible to encode DTMF digits as part of the audio stream, this method is not typically used because it can be difficult to accurately detect and process the DTMF tones.
In summary, the correct statement is B: Cisco Unified CCX receives the DTMF digits in the RTP payload based on RFC 2833. This method allows for reliable and accurate transmission of DTMF digits, which is essential for call center operations that rely on automated IVR menus and other telephony applications.