> We have a 2 telephone lines in our office.
So you will need two FXO interfaces. You could use a TDM400 card for
this with 2 FXO modules. We have 2 X100P FXO cards for our two phone
lines.
> 8 to 10 phones lines.
You mean to connect phones, right?
If you use SIP phones on a LAN, you only need the phones and can use
any number of them.
If you use analog phones, you will need FXS interface, one module for
each. The TDM400P will accept up to four of these modules, I don't
know if you can put more than 2 cards in one box.