Cisco Unified SIP SRST 4.1
Restrictions for Cisco Unified SIP SRST 4.1
76
Cisco Unified SCCP and SIP SRST System Administrator Guide
OL-13143-04
Restrictions for Cisco Unified SIP SRST 4.1
•
Cisco Unified SRST does not support BLF speed-dial notification, call forward all synchronization,
dial plans, directory services, or music-on-hold (MOH).
•
Prior to SIP phone load 8.0, SIP phones maintained dual registration with both
Cisco Unified Communications Manager and Cisco Unified SRST simultaneously. In SIP phone
load 8.0 and later versions, SIP phones use keepalive to maintain a connection with
Cisco Unified SRST during active registration with Cisco Unified Communications Manager.
Every 2 minutes, a SIP phone sends a keepalive message to Cisco Unified SRST.
Cisco Unified SRST responds to this keepalive with a 404 message. This process repeats until
fallback to Cisco Unified SRST occurs. After fallback, SIP phones send a keepalive message every
two minutes to Cisco Unified Communications Manager while the phones are registered with
Cisco Unified SRST. Cisco Unified SRST continues to support dual registration for SIP phone loads
older than 8.0.
Information About Cisco Unified SIP SRST 4.1
•
Out-of-Dialog REFER, page 76
•
Digit Collection on SIP Phones, page 77
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Caller ID Display, page 78
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Disabling SIP Supplementary Services for Call Forward and Call Transfer, page 78
•
Idle Prompt Status, page 78
•
Enhanced 911 Services, page 78
Out-of-Dialog REFER
Out-of-dialog REFER (OOD-R) enables remote applications to establish calls by sending a REFER
message to Cisco Unified SRST without an initial INVITE. After the REFER is sent, the remainder of
the call setup is independent of the application and the media stream does not flow through the
application. The application using OOD-R triggers a call setup request that specifies the Referee address
in the Request-URI and the Refer-Target in the Refer-To header. The SIP messaging used to
communicate with Cisco Unified SRST is independent of the end-user device protocol, which can be
H.323, plain old telephone service (POTS), SCCP, or SIP. Click-to-dial is an example of an application
that can be created using OOD-R.
A click-to-dial application enables users to combine multiple steps into one click for a call setup. For
example, a user can click a web-based directory application from his or her PC to look up a telephone
number, off-hook the desktop phone, and dial the called number. The application initiates the call setup
without the user having to out-dial from his or her own phone. The directory application sends a REFER
message to Cisco Unified SRST, which sets up the call between both parties based on this REFER.
For more information about OOD-R, see
Out-of-Dialog REFER
from the
Cisco Unified Communications
Manager Express System Administrator Guide
.
