IP phones in different IP subnets

[rfpup]

As below, all the IP terminals are registrated in the same Gatekeeper (they are registrated in the same LIM) and they all are placed in the same network or subnetwork.


From Alex:
"If the call is between IP terminals in the same LIM (the terminals are connected to the same IP network), the time slot 0 is dedicated for H.323 signalling, i.e. call control, but the transmission of the media (voice, video, data) is conveyed through the IP network, see Figure 5-3 . "

Question:

If the IP phones are registrated in the same LIM (in the same gatekeper) and the IP phones are not in the same network or subnetwork which will be the path of communication? Will ELU32 consider this call as a gateway call? Is it needed that each of the IP phones can ping to each other?

Thank you

 

[fouesnant]

Hi

First, the ELU32's of one LIM must belong to the same network.
Second, you must specify a gateway to that network if the IPPhone are located in a subnetwork or an other network.
Third :how will you establish a call if the 3 parties (ELU32 + 2 IPphones) cannot ping each others?

The H323 signalling with establish the call from the ELU32 to the Ipphone (throught the Gateway if not in the same network) and the media will be established between Ipphone, but this implies that IP forwarding is established between your networks and that H323 protocol can also be passed throught

 

[rfpup]

Thank you fouesant,

First condition is fulfilled.
Second condition is also fulfilled.
Third:
So media stream in this case will pass from one IP phone to the other IP phone, even they are in different networks.
I thought IP phone 1 sends all the packets(signalling + media stream) to ELU32 and the ELU32 sends all the packets (signalling + media stream)to IP phone 2.

 

[fouesnant]

Hi rfpup

Nope : the H323 signalling is send for establishing the call and then supervising it for service are release purposes.
When the call session arrive on the ELU32, the gatekeeper analyse the called party and detect that it is also IPPHone (in our case), and as registered on the gatekeeper, the Gateway part of the ELU32 is not involved.
The media stream therefore goes from IPPhone to IPPhone; ELU32 Gateway part is only involved when the support is changing ie from IP to TDM and vice versa.