If you do it this way then the burden of providing proper integration between the Ericsson and Unity will lie on the CCM and your choice of gateway. I've seen this done with mixed results and from the Unity point of view there's not much we can do to support it.
I would instead recommend using Unity’s standard dual switch topology as shown in the integration guides, e.g. Unity uses the Skinny tsp to connect to CCM via IP and the Dialogic tsp to connect to the Ericsson via analog lines. Here’s the link for the Ericsson…
