[Elephone P8000] kezmdor:
Disclaimer:

This fix is based on the work of wmn79, his thread concerning this issue can be found here: http://xdaforums.com/google-nexus-5/general/mod-loose-roaming-r-mvno-home-network-t2969702

Backup your system!

This fix works for me and I share this with you. I am not responsible for any damage to your phone or any data loss you encounter.

Symptom:

When connecting to home mobile network you have to enable data roaming in order to get data working.

Cause:

Your mobile provider is using different MNC numbers which are not recognized by Android as a non roaming network.

Fix:

According to wmn79's thread we can fix this by modding the framework-res.apk of Android. He mentions in his thread to push the modified apk with custom recovery update.zip. As I want to stay on stock rom this is no solution for me and fortunately there is a way without custom recovery.

Root your phone. I am on stock 090915 (OTA) and it came pre-rooted. All I need to do was installing SuperSU from Playstore.

Copy framework-res.apk from /system/framework to your computer

Install apktool (http://ibotpeaches.github.io/Apktool/install/)

Install framework: "apktool if framework-res.apk"

Decompile framework-res.apk: "apktool d framework-res.apk"

Edit/Create Files in created framework-res folder (details below)

Compile framework-res.apk: "apktool b -c framework-res"

Copy the modded framework-res.apk (It is inside the framework-res/dist folder) to the Downloads folder of your phone. Do not copy it directly to the /system/framework folder!

Use your favorite file explorer (I use ES File Exporer), mount /system read/write and move the framework-res.apk from your Downloads folder to /system. Again, do not move it to /system/framework folder!

Inside the /system folder check and correct the permissions of the file, it should be rw-r--r-- and should belong to root:root.

Now you should move (do not use copy!) the file from the /system folder to /system/framework

Shortly after this is done on my phone several Google services and apps were killed, just for your information. They work again without problems after a reboot.

Reboot your phone

The process of moving the framework-res.apk to the /system/framework folder is for example in this video: https://www.youtube.com/watch?v=SbjQcFpt39k

So you know how to install the mod, but what is it about? When you decompiled the framework-res.apk there is a folder named "res" inside of the folder "framework-res". In this folder you have to create a new one with the mnc and mcc numbers from your apn settings. I describe this on the example of O2 in Germany. O2 has mcc 262 and mnc is 07. The folder to create is "values-mcc262-mnc07" inside this folder create a file named "arrays.xml". Actually I just copied the hole thing from another folder and edited it to the following contents:

<?xml version="1.0" encoding="utf-8"?>
<resources>
<string-array name="config_operatorConsideredNonRoaming">
<item>26203</item>
</string-array>
</resources>

The item consists of the mcc and mnc number of the network which can be used without roaming. In this example this is the former E-Plus network which is merged with the O2 network. E-Plus network has mcc 262 and mnc 03. I got the information regarding mcc and mnc numbers from this site: http://mcclist.com/mobile-network-codes-country-codes.asp

There can be more than one item in the string-array list.

I have done this, tested it and for me it's working perfectly. You can find my framework-res.apk attached if you are on O2 as well. If you are on a different network and got stuck on my explanation just give me the mcc and mnc numbers and I provide you with a framework-res.apk. As the framework-res.apk is tight to the ROM this will only work if you are on stock 090915.

Caution:

Using a framework-res.apk which is not for your ROM can end in a bootloop!

Cheers