Hammond, thanks for your answer. I made some tests with Asterisk using a softphone and it seems to work pretty good. So you say I need x FXS modules for x analogic phones and y FXO modules for y outbound lines...but do I need a FXO module even if I have a digital line or it is necessary only for analogic lines? I have other questions, please:1) TDM400P card drivers are included in the product (they come with the digiun card) or they must be downloaded from somewhere? I read they must be recompiled with the kernel but I cannot recompile our server kernel or ask our netadmin to do it (he would kill me!!)...isn't there another way to include them inside linux? 2) ...and if I need 20 phones? Should I buy 6 TDM400P cards? Our server hasn't got so many PCI slots...is there another solution (or card)?