A good place to begin would be to connect your buttset to the paging output of the phone system and see if you can hear an announcement when someone presses the soft key and pages. Make sure you're buttset is in the monitor position, not offhook.
If it doesn't work, try dialing the page code instead of pressing the paging soft key.
Another good place to start would be to connect your buttset to the tip and ring input of the v-2003, go offhook, speak into your buttset and see if your voice can be heard over the loudspeakers. Make sure the v-2003 battery feed switch is on when testing this way.
The v-2003 will accommodate either a trunk port or a page port from the phone system. A page relay from the phone system must be connected to the v-2003 when using a page port.