You must acquire a call lock before using any call control functionality for a device. This avoids multiple applications using a device at the same time. By acquiring a call lock before using any call control functions, applications can co-exist without interfering with each other.
However, if acquiring the lock fails, then another application is already using the device. In that case, your application must not use call control functionalities for the device. After the call has ended, you must also release the call lock.
Moreover, as detailed in Managing Calls, when you choose the Easy Call Control module, the high-level methods handle most of the complexity, including automatically acquiring and releasing a call lock.
Nevertheless, you must consider that if the Jabra device cannot acquire a call lock, you cannot use the device for Easy Call Control.
On the other hand, if you require the greater flexibility of the Call Control (CC) module, you must manually acquire and release the lock.