IP Telephones loosing time (3300)

[12345kevin]

We have a cluster of 2 3300's running MCD 6.0 SP2 (12-0-2-23) The 2 systems are in different locations and apart from the networking etc are treated as 2 seperate systems. 1 system has approx 5 per cabs as well as IP phones.

After approx 1 month the IP phones on both systems start to loose time, approx 1 minute per month. The system uses NTP for the time and the 3300 keeps time accordingly. The Supersets on the Per Cabs keep time perfectly which is how it came to light with 2 different types of phone in the same office.

It's not a major problem but the customer has asked us to investigate ? Any clues ?

 

[bobcheese]

I was once told by Mitel support that the time on an IP phone was not a 'clock' it was a 'representation of time' .

Anyhow, are you saying that the time of the IP phones differ from the time on the controller? If so, do all the IP phones show the same incorrect time or are they individually out?

 

[LoopyLou]

Does it correct itself if you go off hook?

You can't duct tape stupid.

 

[12345kevin]

Yes the IP phones differ from that of the controller and all appear to be out by the same amount. Resetting the phones will correct the time on the individual phones.

 

[bobcheese]

Its non-event issues then. Are these phones not in use for a long period?

 

[12345kevin]

Its a reasonably busy system with approx 200 IP phones on each site and 400 DNI Supersets. The phones are definetley being used regular as some are in the IT Dept, 5320's I believe. Although the other site has mostly older 52xx phones so phone type doesn't appear to be relevant.

 

[boycey9]

The phones do not use NTP, NTP is used only to maintain the time on the controller/server.
The display on the phones gets updated with the date/time every minute during its handshake with the controller which normally occurs every 30 seconds. The time only gets updated to minute acuracy if a phone receives the time from the controller at 13:00:59 then the time that gets passed to the display is 13:00 so the phone display time is 59 seconds different to the actual controller time.
Because all the phones connect and get their updates from the controller at different times during a 60 second period it will be noticeable with phones that the time appears different
Please note the phones are not advertised as being accurate time pieces.

Mitel phones usually get their time updated by different methods I will describe each below.

5312,5324 type phones
The 5224 gets its time from the Call Control. The clock time is not maintained on the phone and is updated by a refresh of the display every minute or when a call is made. This can cause the time to appear to be different by up to 1 minute. If the call control has the time 09:30:59. The time will get displayed on the phone for the next minute as 09:30 so there is automatically the possibility of a 1-minute difference.

5330, 5340 & 5360 type phones
The time on the 5330/40 & 60 is maintained locally by the phone. The time is updated to the phone by a similar method to the 5312/24 so only details of the hours & minutes are sent so there is the possibility that the time could again be 1 minute difference. Then there is the possibility of drifting of the clock during the day as the phone is only updated with the time once a day

To show how time can differ on phones the following example shows two phones being updated 1 second apart
Phone 1 gets its update
System time = 09:00:59 Phone1 time - Display = 09:00 Actual = (09:00:00)
Phone 2 gets its update
System time = 09:01:00 Phone1 time - Display = 09:00 Actual = (09:00:01) Phone2 time - Display = 09:01 Actual = (09:01:00)

On top of this the 5312/24 & 5330/40/60 get their times from different clocks so there is potentially a difference in time maintained in their source clocks

The phones are not advertised as being accurate time pieces and the time is only maintained to the minute.

 

[jabbo99]

Boycey9, do the same rules apply to the SX200 ICP? Just yesterday, I noticed that time on the IP phones were different. The 5540 IP console and one 5340e was the same time as the controller. The other two 5340e's were approximately 1 minute behind. I reset the IP phones from the MTCE. Again, two phones had the same time as the controller, while the other two had a different time. Restarted the system from MTCE. The console had the same time as the controller but now all three 5340e's displays are showing that they're approximately 1 minute behind the controllers time.

Curious, I'm assuming that analog phones use the controller's clock to tell time?