Cisco UC 520 PoE

The Cisco UC 520 has 8 PoE ports out of which you can draw 88 watts of power. This means that with each Cisco IP phone drawing 12 watts of power, you can only have 7 IP phones (= 84 watts) on the 520.

If you don’t know this it can be quite hard to troubleshoot, because the phone doesn’t get enough power to create a link, so it looks as if the port itself is dead.

If you are planning to implement the UC 520 in an environment with exactly 8 phones, remember to add the companion switch to the solution so that you have enough power to support all phones.


H.450 is an umbrella protocol to support supplementary services in H.323.

It is subdivided into

  • H.450.1 Generic functional protocol for the support of supplementary services in H.323.
  • H.450.2 Call Transfer supplementary service for H.323.
  • H.450.3 Call diversion supplementary service for H.323.
  • H.450.4 Call Hold supplementary service.
  • H.450.5 Call Park supplementary service.
  • H.450.6 Call Waiting supplementary service.
  • H.450.7 Message Waiting Indication supplementary service.
  • H.450.8 Calling Party Name Presentation supplementary service.
  • H.450.9 Completion of Calls to Busy Subscribers supplementary service.
  • H.450.10 Call Offer supplementary service.
  • H.450.11 Call Intrusion supplementary service.
  • H.450.12 ANF-CMN supplementary service.

In Cisco CME it is important to remember to enable H.450.12 in addition to the default subprotocols for redirection of calls to work.