Connecting Pascom based on Asterisk to PSTN wall socket

Hi all,

First i am using a Pascom system based on Asterisk, and it’s locate at German, and we have many branches around the world, so the problem is right now, we need to connect 4 PSTN Egypt lines to our System in German, so we can send and receive calls on one IP Phone and we already connected VOIP IP Phones between all branches through VPN, and we are using IP Phones Brand Called Yea Link Phones, and it act as a bridge, so when i read up i found this can be done by SIP Gateway called BeroNet FXO / 4 FXS Small Business Line Gateway - ( Model : BFSB4XO4XS ), so we bought it but when i receive the device the Ports was RJ45 Lan ports not Analog RJ11 Ports, and i was thinking how to connect wire system wire system using 48V DC to this Device ?? i think about warp the two wire phone to RJ45 so i could connect it to Beronet Device, but the problem, does this will work out and this Beronet device read recognize that line is a PSTN line ?
SO the Project is ;

First i need to connect 4 PSTN lines to our Pascom System in German.
Second : I need a recommanded and tested Device called do that.
Third : When we connect all to eachother, we need to use one IP Phone for both ( VOIP and Landlines ).
Fourth : When all this happened, I think i will make a PBX for Landlines to pull a line like ( Number 5 ) and the rest Extensions will work as it used to.
Fifth : When i receive a local call, Whoever is calling we hear our main IVR messages.
Sixth : We will have to active waiting message.

Please advise and help if anyone get through this situation please.