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Cisco SPA504G freeze

Level 1
Level 1

We have 7 SPA504G phones recently deployed, connected to an ESW 520 24P PoE switch.

At very random times, a phone will "freeze" such that the screensaver is stuck and the time displayed on it stands still.  Pressing keys on the phone including menu button do not show any results on the screen of the phone.

Oddly, I was able to ping the phone when this happened and also load the web interface in my browser.  The web interface shows the current time on the phone being the same time that is "frozen" on the screensaver.

This doesn't seem to be related to a calling or QOS issue as my phone froze at 6:18am before anyone was in the office.

All phones are running the current latest firmware, 7.4.6

95 Replies 95

FYI, dev has a fix for the stun lockup issue.  The fix will be in the next release.  Thank you.

Level 1
Level 1


Cisco released new firmware for the SPA504G - 7.4.9a. I have updated my test phone and have been testing this issue for the past 20 minutes--I can't seem to get it to freeze! It may be premature to say this but from the looks of things, this issue might actually have been fixed!

Everyone, please update your phones to 7.4.9a and test. Let's hope this issue is finally behind us!

We're experiencing the "Check DNS" issue with 504G 7.4.8a. Today i upgraded the firmware to 7.4.9a- nothing changed- I still get this hung after reboot.

Level 1
Level 1

I have the same issue with the SPA 502G running firmware 7.4.8 on a UC560. I have a customer with 20 of these phones and this is a bug that needs to be sorted. I cannot see why this hasn't been fixed yet or at least why are we not made aware of it through the Cisco Partner Channels.

Can anyone confirm an actual fix yet? My customer has just random phones freeze overnight and then they need rebooting in the morning. I noticed reading through this thread that there are some issues with having the phones watched, my customer has all of their phones watched which is a critical thing for their business.

The latest firmware, 7.4.9c, fixes the issue. Upgrade the phones to 7.4.9c and you're set.

I am running 7.4.9c on a SPA504G and I am still experiencing issues with random freezing. I have tried the measures you indicated above, but that doesn't cause anything to happen, which leads me to believe the root cause of our problem is different.

We have 7 of these phones and they all freeze at seemingly random intervals - generally sometime in the late evening or early morning, but never at the same time.

I'm going to try a couple things first, but I may try and replace the switch they all connect through. It is rather old and is the only thing that remains in the equation after we redid our network a few months back (were having the issue then, too).

7.4.9c does not completely fix the SPA504G freeze problem.  We have 12 SPA504G phones that I upgraded to 7.4.9c on Jan 4, 2012.  Since the upgrade, the frequency of freezing has been greatly reduced but it still occurs randomly.  I get about 1 or 2 reports of phone freezing a week.  When the phone freezes, the time displayed is stuck constant and the phone is unresponsive.  Rebooting is the only way to restore functionality.  Assuming the constant time displayed on the phone is the time that phone froze, most of these occur during off business hours.  Here are some example freeze times: 9:12pm, 2:23am, 2:13am, 1:22am, etc.

Still experiencing issues with random freezing of SPA504G phones running 7.4.9c firmware.  I am working with my service provider to try to prevent this problem.  Here are a few things we have tried:


1/4/12 - update to 7.4.9c firmware

1/17/12 - perform factory reset and reprovision phones

2/28/12 - disable provisioning and firmware updates in phone web settings

Lockups since 2/28/12:

User1- 3/1/12, 1:06am; 3/15/12, 10:50pm
User2- 3/1/12, 2:04am
User3- 3/8/12, 10:35am; 3/19/12, 5:15pm
User4- 3/15/12, 10:59pm
User5- 3/16/12, 8:17am
User6- 3/15/12, 11:37pm


Are the phones pingable when they freeze? Can you open a web browser to a phone in that condition and save the web page?  The info page has a reboot reason code that might give some additional info.

Also can you enable debugs on one of the phones and capture the output to a syslog server.

We can look at the output and determine if any network event (i.e SP server failover) caused the hanging condition.



Generally, employees need to use their phones so they reboot them right away when they discover they are frozen and I do not get a chance to do any diagnostics unless it is my own phone.  As it just so happens, I came in this morning and my phone was frozen.

The physical interface on the frozen phone itself is not responsive., there is no dial tone, the time and date are frozen, the LCD backlight does come on though if a button is pressed or you lift up the handset.

I can successfully ping my frozen phone.

I cannot access the frozen phone web interface.

We are a small business and we do not really have a dedicated IT expert that maintains our phones.  We are using a hosted IP phone service, so we just have the phones at our site and the server is located at and maintained by the service provider.  I do not currently have a syslog server, is there syslog server software that you would recommend for Windows?  Also, can you describe exactly how to enable phone debugging?

Each particular Cisco phone only seems to lock up once every two weeks or so, so it could be a while before my phone locks up again.

I understand the critical nature when the phone freezes and the end user needs to get back inservice right away.

Can you email me at and I'll coordinate the troubleshooting steps and also inquire on your SP provider (what type of server, etc..)


Randy Bordner

We also have been experiencing the same issue.  We have a mix of (10) 504 & (6) 942, the 504 are more problematic.

Have tried 7.4.5 to 7.4.9c (all inbetween) and still have lockups.

Provider is Nextiva, they have tried most everything on their end as well.  Lockups freeze the client computer connected to the PC port.  No web access, no menu access, frozen clock time really gives it away.


I have nextiva as our provider and SPA504G phones.  Experiencing same lockup issues on two of our phones.  Have to unplug to fix the issue.  After reading this whole blog I am even more confused as to what to specifically try to fix the problem.

We also use Nextiva as our IP phone service provider.  Cisco has been working with Nextiva and others to try to dianose the freeze problem.  Nextiva is currently testing a new version of SPA504G firmware that is supposed to fix the freeze problem.  Once they are satisfied that it is a solid solution they will roll it out to customers.  Talk to Nextiva customer service about getting on a list to be notified when the solution is ready.

As a Nextiva customer, I am very glad to hear this. We have tried everything we can think of, and while some of the solutions have helped a little bit, nothing has completely solved the problem.

Some of what we have tried that seems to have somewhat helped is:

  • Set static IP's both at the router level (to reserve them) and also on each phone
  • Changed DNS to point to OpenDNS
  • Replaced the switch connected to the phones

These seemed to have helped in our situation, but no guarantees that they will help everyone. I will be calling Nextiva to find out how to get on that list.


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