Push Notifications On My IPhone 4 Are Not Working

I purchased my iphone in California under an AT&T contract. That contract is now over and now my Iphone is unlocked and I'm using a company called Tchibo where I put money onto a SIM card and use it as needed.

My PUSH NOTIFICATIONS NO LONGER WORK 😟

Also, FaceTime and IMessage are not working either 😟 😟

I have tried numerous things like:

-Restore

-Downloaded this so-called PersistentConnectionLogging.mobileconfig for my iphone settings (it did download and I restared the phone=nothing!)

Now does anyone have answers to my question? It seems rather simple and here is goes:

How do I fix my Iphone 4 so that all of my PUSH NOTIFICATIONS work?

Yes, I did "Unlock" my phone from AT&T and have a sneeky feeling that somehow now ITunes doesn't recognize my Tchibo SIM card? I'm not a very computer savy person but I would appreciate it IMMENSLY if someone can please help me out here. Any suggestions are welcome.

Thank you all very much!!! And happy new year 🙂