Cisco 8845 Phone does not go into Limited Functionality Mode

[rousseaua]

We have two Cisco 8845 phones in our environment, the rest are 7900 phones. If the internet goes down for whatever reason, the 7900 phones go into limited functionality mode and will not allow any calls to be made or received. The 7900 phones will function as basic phones allowing incoming and outgoing calls. Do I need to change a setting in the environment to allow for limited functionality on the 8845 phones, or is that not an option with the phones.

[Chris Deren]

You listed 7900 as going into limited functionality as well as basic, I am sure you meant to list 8845 as one of them, please correct.

Also, explain what do you mean by "limited functionality" and "basic"? Are you referring to SRST configuration?

If so, 79XX are usually running SCCP firmware and 8845 are SIP, so they require different SRST configuration on local GW, make sure you have SIP SRST configured.

[rousseaua]

Most of our phones are in the 7900 series. We have two newer phones that are 8845. If the internet goes out, which it has several times, all of the 79xx phones will show in the screen Limited Functionality Mode and still allow calls to be made and come in. The two 8845 phones don't, you cannot make calls or receive calls if the internet is out. 

I am not too familiar with the Cisco phones. I am new to this position (3 weeks now), and have only worked with Avaya in the past. Different firmware makes since, but where would I go to check what it is running and the SRST configurations? Thank you!