if you watching the error message on your smart android phone "Unfortunately the process.com.android.phone has stopped" after you installed a new ROM or a system updated your firmware/firewall restrictions, it actually a couple of ways to fix it.
The error message is triggered by the phone or SIM toolkit application. So,if you are constantly getting the "Unfortunately the process.com.android.phone has stopped" error on your smart android phone, So dont worry about is,Here are ways to fix your device
1 : Clear Cache and Data of the Phone App
To access this option, go to Settings. Then, select Apps. Tap the All tab so that all the apps of your device will be displayed in a column. Scroll down until you see "Smart Phone" or an option similar to it. Tap it, followed by selecting the "Clear Cache" option. If the problem persists, repeat the steps and include “Clear Data” in your actions. Reboot your phone for the changes to take effect.
2 : Clear Cache and Data of the SIM Toolkit
Repeat the steps shown above. But this time, choose SIM toolkit from the list of apps under the All tab.
3 : Fix Using Custom Recovery
Install the latest file manager. Use it to delete the cache or temporary folder of "Smart Phone" as well as the SIM toolkit app. Reboot your device for the changes to take effect.
4 : Reset the Phone App on your Android device
To do this, open from your home screen the menu and then the Settings. Search there for "Application Manager" and tap on it. In the Application Manager itself, switch to the tab "All" and then search for "Telephone". Have you found the entry in the list, tap on it to open the app information.