I'm going to install a standard Valcom one-way paging setup .....15 watt horns / V1036 models etc off traditional pbx ...The customer wants a door ringer / door bell to ring paging horns.....so getting a Valcom v9927 for that..... for the "door bell switch/ button" I'm assuming I can use just a standard door bell (no voltage on it) and run the main leads directly to v9927a ring generator and that will emulate a "dry contact closure" and ring the horns....is this correct?
Thanks.

Yes you are correct, wire the push button to COM and Tone 1-8 for the sound you want. If you have more than one button, the lower number will have priority.

Thanks!