- preconnect phone before checking BT modem

src/bt_call_controller.py

@@ -42,13 +42,18 @@ class CallState(bt_phone.Observer):
 
 
 # Listen to call changes
-CALL_STATE_EVENT = CallState()
-PHONE = bt_phone.Phone()
-PHONE.addObserver(CALL_STATE_EVENT)
+CALL_STATE_EVENT = None
+PHONE = None
 
 # virtualmic module
 PA_MODULE_IDX = -1
 
+def init():
+    global CALL_STATE_EVENT, PHONE
+    CALL_STATE_EVENT = CallState()
+    PHONE = bt_phone.Phone()
+    PHONE.addObserver(CALL_STATE_EVENT)
+
 
 # Set volume 0..100%
 def set_headset_spk_volume(vol: float):