Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

How do IP phones get date and time from CME

Multiple methods are used to send Date and Time information to IP phones registered with CUCME (Cisco Unified Communications Manager Express) . The type of method used depends on the phone type and protocol (SIP or SCCP). In this document, we will take a look at some of the common deployment scenarios.

SCCP : 7902G, 7905G, 7912G, 7920, 7921, 7935, 7936, 7940,  7960, 7985G

SPCP : SPA 500 series

1) IP phone requests Time and Date information from CUCME at the time of registration. CUCME provides the time and date based on the following configuration :

clock timezone PST -8
clock summer-time PST recurring

We can verify it by enabling "debug ephone detail mac-address <mac-address of the phone>".

Snip from "Show log" :

026782: Nov  8 02:23:17.983: ephone-9[8/3]:TimeDateReqMessage
026783: Nov  8 02:23:17.983: year=2010 month=11 day=7
026784: Nov  8 02:23:17.983: hour=18 minute=23 second=17
026785: Nov  8 02:23:17.983: day=0 dayofyear=311 tzoffset=-28800
026786: Nov  8 02:23:17.983: ephone-9[8/3]:DefineTimeDate sent

"tzoffset" is the offset from the GMT time in number of seconds. In this example, PST timezone is used and hence "tzoffset" is set to -28800 (3600 * -8). IP phone uses this information to sync its internal clock and displays this time.

2) CUCME also sends Time and Date information whenever the administrator manually changes the router's time using the "clock set" command :

Router#clock set 01:58:00 07 Nov 2010

Snip from "Show log" :

013835: .Nov  7 08:58:00.000: %SYS-6-CLOCKUPDATE: System clock has been updated from 06:21:31 PST Mon Nov 1 2010 to 01:58:00 PST

Sun Nov 7 2010

Sun Nov 7 2010, configured from console by cisco on vty0 (x.x.x.x).
013836: .Nov  7 08:58:01.379: ephone-9[8/2]:Update Phone Clock
013837: .Nov  7 08:58:01.379: ephone-9[8/2]:Update Time and Date
013838: .Nov  7 08:58:01.379: year=2010 month=11 day=7
013839: .Nov  7 08:58:01.379: hour=1 minute=58 second=1
013840: .Nov  7 08:58:01.379: day=0 dayofyear=311 tzoffset=-25200
013841: .Nov  7 08:58:01.379: ephone-9[8/2]:DefineTimeDate sent

SCCP : 7906G, 7911G, 7941, 7942, 7945, 7961, 7962, 7965, 7970 and 7971

These type of phones support a parameter called "timeZone" in their XML based configuration file (SEP<mac-address>.cnf.xml). Snip from IP phone configuration file :

<timeZone>US Eastern Standard Time</timeZone>

CUCME sets the "timeZone" parameter depending on the following configuration :


  time-zone 13

Note: 13 refers to EST timezone.

1) When the phone registers to CUCME, it requests date and time information using the "TimeDateReqMessage" to determine the GMT timestamp.

2) It then adjusts the time according to the "timeZone" parameter in the configuration file and displays the adjusted time.

SIP : 7906G, 7911G, 7941, 7942, 7945,  7961,  7962, 7965, 7970, and 7971

Method 1

1) IP phone obtains the GMT time and date information from the "Date" header of SIP 200 OK response of SIP REGISTER request. We can verify it by enabling "debug ccsip message" in CUCME

Snip from "show log" :

027275: Nov  8 02:56:37.591: //-1/xxxxxxxxxxxx/SIP/Msg/ccsipDisplayMsg:
SIP/2.0 200 OK
Via: SIP/2.0/UDP;branch=z9hG4bK62d46dd7
From: <sip:1000@>;tag=001d705ea9fe0166626a9517-440eb08b
To: <sip:1000@>;tag=ACE5C58-20F
Date: Mon, 08 Nov 2010 02:56:37 GMT
Call-ID: 001d705e-a9fe0002-7df8ade2-a17f62fb@
Server: Cisco-SIPGateway/IOS-12.x
Supported: X-cisco-srtp-fallback
Contact: <sip:1000@>;expires=0
Expires:  0
Content-Length: 0

2) After successful registration, it adjusts the time according to the "timeZone" parameter in the  configuration file and displays the adjusted time. SIP based CUCME sets the "timeZone" parameter based on the following configuration :

voice register global
  mode cme
  timezone 13
  create profile

Method 2

These phone types running SIP protocol also support NTP and can get time information directly from the NTP server. Snip from the phone's configuration file :

<timeZone>US Eastern Standard Time</timeZone>
<ntp priority="0">

SIP based CUCME sets the NTP server and timezone value based on the following configuration :

voice register global
  mode cme

  ntp-server mode unicast
  timezone 13
  create profile 

As a best practice, it is recommended to configure same timezone value in "clock timezone", "timezone" (under "voice register global") and "time-zone" (under "telephony-service") commands.

New Member

Great materials, which helped us a lot, but just to mention that after applying new configuration in telephony-service section, it is necessary to re-create cnf-files by "create cnf-files" command.