Pagin and Intercom Toruble

I am running FreePBX 2.9.0.9. When someone pages using the Paging and Intercom group we set up it is coming through the handsets of users who are speaking on the phone dropping their calls. Any ideas?

What phones are you using?

Check the Paging and intercom settings at the bottom it says Busy Extensions. Make sure skip is selected. Probably already looked at this.