If you reject a call, it can be incredibly frustrating, especially if you look down and see that your iPhone has full coverage. Although there are a number of problems that can cause this, one common and often overlooked problem is that your iPhone does not switch the cell towers as needed.
Failing to switch to the corresponding tower will cause a problem with communication between your smartphone and the mobile network. Either your iPhone is trying to connect to a cell tower that is far out of range, or the new cell tower is already overloaded with other connected devices.
How cell phones change towers
Cell phones work with networks to determine this The best tower for connection based on range, signal strength and frequency. When a phone is connected to a cellular network, it continuously checks the signal strength of nearby towers and transmits that information to the network. Theoretically, if a phone's connection to a cell tower falls below the signal strength of a nearby signal, the network should switch the phone to the new tower.
In practice, however, this does not always happen as smoothly as it should and frequent bug fixes such as cycling Airplane mode do not always work. If the "Reset Network Settings" option always works, this is a drastic step that also deletes all saved Wi-Fi credentials. Fortunately, there is another easy way to force your iPhone to toggle towers.
Step 1: Install OpenSignal
OpenSignal is a network performance monitoring app that not only shows you the speed of your connection, but is also currently connected to. You can search directly for "OpenSignal" in the iOS App Store or jump directly to it via the link. Install just like any other app.
Once OpenSignal is installed and open, you will need to place it in the notification prompt at your location to get access. OpenSignal uses your location to show you nearby cell towers.
The app also asks you if you want to contribute signal data. OpenSignal uses this information to assess the carriers and provide customers with information about which carriers offer the best coverage in a particular region. This is completely voluntary, but if you choose, all information collected will be strictly anonymous.
Next you will see a screen with an arrow pointing to the tower with which your iPhone is currently connected. You can also tap the arrow to see a map of all nearby towers operated by your carrier. You will check this after pressing a button to confirm that it was successful.