com.android.phone is the name of the process that handles the network service of your phone,so without this process you won’t be able to make/receive calls nor browse the internet,the only option you have is Wi-Fi and bluetooth, NFC and every other wireless connections independent of your SIM network.
Now how do I solve this problem?
What your android phone is trying to tell you is that, you have tampered with either one or both of this system applications "phone.apk" or "telephonyprovider.apk" you probably disabled it with a third party application or you uninstalled it with an application that has special privilege. Or maybe you altered the properties of one of the applications. Any form of alterations would cause your phone to give this error messages.
So how do we solve it?
It depends on what happened. If you are at any point able to use your network service either to browse the internet or to make a phone call or it goes on and off but it’s not stable,then you still have hope. It means the files phone.apk and telephonyprovider.apk are still intact but a little damage has been done to them. How do you know if these applications are still in place. Use a special file explorer like Smanager or any good one that has root capability, go to the root of your phone,(that is outside your memory card and internal memory card) ,open the "system" directory then open "app" directory,scroll down the list of applications, if you find phone.apk and phone.odex, good; scroll down again till you find telephonyprovider.apk and telephonyprovider.odex if you do then Congrats.
What you need to do now is to go back to the root of your phone and open the "data" directory, then open "dalvik-cache" directory,do a multiselect to select everything you find in it, and delete all,confirm to delete all. After deleting all,switch off you phone and turn it on. You would see something like "Android is upgrading" ,wait till your phone finish booting, then watch your network service come back on loading.
If you belong to the category where you can’t find any of the specified applications or files above,then you need to get the application or specific missing file from another phone similar to your. You can’t find it anywhere to download,you have to meet a friend who uses a similar phone as yours(same manufacturer and same android version) (although a miracle can occur to make the application from another android version to work). Use the file explorer on your friends phone to get to the app directory of the system directory of his root. Share the missing application or file to your own phone,download "system apps installer" from play store into your phone, so that you can install the missing application as a system application,after downloading "system apps installer" click on the phone.apk or telephonyprovider.apk and select system Apps installer as the option to install it. If it the odex file that is missing,simply place the corresponding odex file at the app directory of the system directory of your root, and confirm every action by Smanager or whatever you are using. After installing the system app wipe dalvik-cache as explained above then switch off your phone and turn it on back(note that I didn’t say reboot your phone).
If after everything the problem still persist,try another app from another phone more closely related to your phone,but make sure you delete the previously installed one before installing another one to avoid signature mismatch.
If after trying different app (phone.apk or telephonyprovider.apk) the problem still persist,then I am afraid you have to flash your stock ROM. Take your phone to where you bought it and ask for a repair. Don’t tell them you did anything wrong,they will fix it for you or replace the phone if it’s still under warranty.