keyless entry

My outlander is the basest of base. No options at all. No keyless entry. But if I put the key in the drivers door and turn it, it unlocks all the doors. So does anyone know if just a keyfob is all I need to do remote unlocking or will I require a receiver? Not sure if the receiver was installed in all of them or not.
thanks
-terry

I think you might need the receiver. So the key does unlock all the doors from the driver's door?

you may be lucky and have the receiver, but I wouldn't get your hopes up. My 84 Volvo would also unlock all doors by unlocking the drivers door with the key....no keyless entry there! call parts dept at dealer, they'll tell you what you need to add.