Connecting Digium TDM400p to router with telephone socket for free calls

Hi everyone
I am using TB 2.8.04
Digium TDM400P
1x Digium FXS module
1x Digium FXO module
Single pstn line
3 x voip numbers
The above works without problems.

But I also have a Alice box router with a telephone connector for free calls (via voip).
I would like to make use of this.
So the question is would I need second FXS and FXO modules in the TDM400p then route outgoing pstn calls to my alice box ( I am not interested in incoming calls on this number but would change outgoing number to my pstn number).