Device Pool

A Device Pool is a simple method of configuring the same parameters for a set of devices.Once you assign a device to a Device Pool, it inherits those parameters configured for the Device Pool. The seven mandatory settings are :

  • Call Manager Group
  • Date/Time Group
  • Region
  • Softkey Template
  • SRST Reference
  • MLPP Indication
  • MLPP Preemption

Call Manager Groups

Cisco Call Manager groups can be used to specify a prioritized list of up to three Call Manager with which Cisco IP Phones can register. You assign a Call Manager to a device through a Device Pool

During a failover transition , active calls are preserved and phones will re-register once the existing calls are complete.

Regions

You use Regions to specify the codec and the maximum video bandwidth that can be used on calls between devices .

Every device is in one Region, and you assign a device to a Region by specifying a Region within a Device Pool and then assigning a Device Pool to a device

MIC,LSC, Security Endpoints

Regarding security endpoints, you have 2 opportunities :

  • Newer phones are using more an existing Mafufacturing Installed Certificate , this is the MIC
  • Meanwhile , old phones will use a Locally Significant Certificate ( LSC) which will be installed by the Certificate Authority Proxy Function (CAPF)

As LSC must be a transaction between the Ip phone and the CAPF , here is the process as it is issued :

  1. IP Phone generates a public/private key pair
  2. A TLS Session is established with the CAPF Service and the keys and identity are sent from the phone to CAPF
  3. The CAPF Service creates and sends an LSC to the phone
  4. The IP Phone installs the LSC

Also for info, the CAPF Service must be in the phone CTL file , which is downloaded from the TFTP when the phone boots .

CAST – Cisco Audio Session Tunnel

Cast is the protocol used into the conversation between the webcam and your IP Phone.

It uses TCP/4224 in both direction ( easy to implement if you are firewalling your networks).

Pay also attention that the communication is only between the IP Phone and the webcam . CUCM is not involved at all in that “conversation” except for the TFTP config download.

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