Try downloading another ROM, transfer it to your device, wipe data, dalvik cache and cache then install ROM. Install googleapps if it suggest. Test to see if the mob network works or not.
This is sometimes an issue for some running a device that has a bit of models. Which tempers with networks.
If you want to be sure about this matter. Reflash the ROM you have installed and see if it does the same.
The sash wringing... the trash thinging... mash flinging... the flash springing, bringing the the crash thinging the...