I'm currently using an iPhone 5s with AT&T and looking to unlock the phone. I travel a lot and it's annoying for me to carry two phones whenever I'm abroad. I use my old unlocked iPhone 4 for international SIM cards equipped with data plans, minutes and texting and I also use my iPhone 5s for taking pictures and other things that require wifi.
I'd like to completely ditch the iPhone 4 (it's just way too slow) and solely use my 5s. I know there are some websites that use an IMEI unlock, but I'm apprehensive with how reputable these websites can be.
Can someone please guide me to the right place or where I want to go? I understand that I have to pay for the unlock.