I have 7 to 8 PSTN lines which I want to use with my FreePBX system.
I was using digium card before with 4 ports but two of them are FXo and two are FXs.
I want to get rid of that card. Is there any gateway or adapter which I can use to trunk with Freepbx and my phone system will be able to utilize those 8 PSTN lines.
Yes. Sangoma and Digium make cards that will do this. If you are looking for something a little more exotic, you can look for Synway.
Most cards of this type have modules that you can add and remove to give you the exact configuration you are looking for, usually in “groups of two”. So, the card will have no modules, and then you add whatever kind of modules you are looking for.