There are multiple reasons why you may not be able to place a call:
You are able to browse the internet, but cannot place a call
You may be able to browse the internet, but be unable to place a call due to low levels of cell signal communication that don’t support sending sound real-time. So, while some cell signal connections let you get to the internet, they are not efficient enough for you to carry on a conversation.
Your mobile device status bar shows that it has WiFi or 3G/4G coverage, but the WiFi/Data indicator in the mobile app shows with two red dots -- it has no connectivity to either WiFi or 3G/4G.
You need to ensure you are connected to the network before launching the app.
To connect to the network, please check that the app is completely closed (it may be running in the background). Connect to WiFi or 3G/4G and then relaunch the app.
If the issue persists, your network signal may not be strong enough. If you are on WiFi, please test your signal strength by moving your mobile device as close to the wireless access point as possible and then attempt to place your call. If you are on 3G/4G, try to move to an area with good reception and attempt to place your call.
You will also want to make sure that your mobile network provider or internet provider’s modem/router does not block forwarding ports 5060 UDP and 13000 UDP. To verify this, you will need to contact your provider or the manufacturer of your router.