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Hello and welcome to a short demonstration video of circuit switched fallback. Circuit
switched fallback is a mechanism by which, when we’re on an LTE data connection and
we receive an incoming voice page, that the UE will drop down to GSM or W-CDMA in order
to accept that call and continue the call under circuit switched conditions. I have
here my UE which is capable of both LTE and of GSM and W-CDMA, and it is connected via
this combiner to a PXT, an 8960. The 8960 here represents the GSM/GPRS cell. The PXT
here represents the LTE cell and the core network. Both of these instruments are connected
via LAN to my demo PC here, a server PC, which I can use to demonstrate data connectivity
as we transfer from LTE data to GSM/EGPRS voice and data.
So the first thing I am going to do is switch my device on, and you will see that I have
connected in to the LTE network here. I am going to demonstrate that we have got data
connectivity by running a ping, and you can see that we have a reply from the IP address
of the device, so this is a data connection in LTE. I am going to switch the GSM cell
on. I am going to select a custom message, which is circuit switch service notification,
and I am going send that to the UE. You will then see I go to idle and I now have an alerting
here, and I am going to accept that. If I put the speaker on, you can see that I have
an echo, so I have a voice echo connection.
You can see that I’m connected. This relates to GSM. The data connection here is suspended.
We are not using dual transfer mode. We could, I am demonstrating this without it. You can
see that my data connection is suspended while I am on the voice call and that my requests
and pings are being timed out for the time being. However, if I end the connection, you
will see that I instantly come back to PDP active and transferring and that my data connection
has resumed on the EGPRS cell. This functionality on the 8960 and PXT is also available for
W-CDMA. Thank you for watching this short demonstration video.