Showing results for 
Search instead for 
Did you mean: 
Walkthrough Wednesdays

Endpoints Call Protocol - H323 or SIP

Curious to see what some other users and/or Cisco guys say about what they use or prefeer when it comes to what call protocol for different endpoints.  It can be endpoints such as C-Series which can use both, or an MCU.  We have a mix of endpoints ourselves that can either be configured with both  protocols or some with just one type, hence the discussion to see what  and how some others choose to configure theirs.

Thanks, Patrick


Hi Patrick,

Ideally both the protocols can work fine on the device. There are some situations where having both protocols can prove to be of advantage. SIP is good for latency and to have very little overhead as compared to H323. If you already have H323 then you can configure SIP on the same device for the following purpose:

  • If another endpoint is trying to make a call to your endpoint which has only H323 registration, this would cause SIP to H323 interworking and a traversal license would be used. Also not to mention the fact that during this call the media would also travel through the VCS Expressway. This could cause too much undesired network traffic which can be avoided by having SIP also configured and having a SIP to SIP call.

  • H323 is used for unique addressing and hence two devices cannot have the same H323 ID or E.164 Alias however, in the case of SIP, you can use that as a BAT Line and multiple devices can have the same SIP URI. Whenever a call is made to that URI, all the devices assigned to URI will ring until one of them answers the call. Hence, it can be used to reach a group of devices rather than just one device.

Hope this answers your question.


Mubashshir Akhtar

Thanks Mubashshir Akhtar

Thanks for the input, most of our endpoints are configured for H323, however we do have some that are using SIP (E20, Jabber).  We've configured our VCS search rules to allow for searches in either direction and capable of locating either device with/without domain, however I'm looking into the prospect of trying remove that need.  What does Cisco do for their H323 and SIP devices, and when it comes to the VCS?

I am afraid, I wont be the best person to comment on that. There are no recommendations as far as I know. We recommend the customers to keep the methods (H323 or SIP or Both)  that they find suitable to be used in their network setup.


Mubashshir Akhtar

Thanks Mubashshir Akhtar
Content for Community-Ad

Spotlight Awards 2021