Hi James,

You are seeing the built-in "Privacy" that comes with using Shared Lines. There is no way to allow the call on the Shared Line to be heard on both the 7936 and 7960 without using cBarge or if moving between the two phones using Hold. Have a look;

If you use a shared line, you can use cBarge to join an in-progress call and convert it to a standard conference. This gives you and all call participants the same features available in standard conferences and you can add additional participants to the call.

When you use cBarge, other parties on the call hear a tone and brief interruption in the call, and call information changes on the screen. When you hang up, the call remains as a conference call provided at least three participants remain.

From this CCM 4.0.2 doc;

http://www.cisco.com/en/US/products/hw/phones/ps379/products_user_guide_chapter09186a008040160f.html#wp1005703

This prevents unwanted people from listening in on our personal conversations.

Hope this helps!

Rob