Release Notes 2.1.8

From Pbxnsip Wiki

Camp On

When a extension received a second incoming call while being on hold and that incoming call was not answered, the caller could use camp on to receive a callback when the extension became available again. Upon going off hold, that created a flooding of callback calls. This loop was fixed in 2.1.8.

The workaround is to either disable the camp on feature or upgrade to 2.1.8.