Troubleshooting the "One Hold" feature
First, confirm you have configured the fake call feature properly by following the steps in this article.
Then check to make sure your device is on and charged. Single tap the action button. Does the device vibrate, and is the LED green? If so, move to the next step. If the LED is blue, please contact POM support.
Next, check your cell phone coverage. If you are in a low-coverage area, the device may take longer than usual to activate the fake phone call.