I'm from the US but in Mexico. I have an old iphone 4s for a while but it has many issues. I have a sim card on this phone. I also have an iphone SE. From what i read online, i could just go and buy another telcel sim card at a telcel place for this iphone SE and they allow me to keep my current number in my iphone 4s. First off, that is true right? The other thing is if i do this, do i have to make sure i backup everything on my iphone 4s to icloud first or not? I read online that the sim card for the iphone 4s isn't the same as the iphone SE so that means i can't switch the sim card right? Someone posted online you can do this by cutting it. First off, is that true or false? They did mention that if u do this, you won't get 4g on the iphone SE. I know i only have 3g on my iphone 4s. Is it hard to cut the sim card etc? So when they put the new sim card in my iphone SE, then i can just use whatsapp like that on my iphone SE? I still have to set it up right? The other thing is what happens to the sim card on my iphone 4s? I assume it doesn't work anymore if thats the case? If I get a new number on my iphone SE, well what happens with whatsapp? Could i still use the same contacts and just change the number etc? The thing is with telcel, we have credit for the phone number. So basically what are the pros/cons of getting a new number vs keeping the old number? If i keep the same number, then that means all my credit that i have on this telcel number i keep right? But if i get a new sim card, well that means i have 2 different numbers right? However i have a decent amount of credit on the iphone 4s. But do i have to do anything now on my iphone 4s before i go to telcel place and buy new sim and request same number? Also how would they confirm that is actually your number? Do they just look at your phone number on the iphone 4s to see this? Or do they do something else? Right now im assuming i just go there, bring both my iphone 4s and iphone SE there. But what about the whatsapp? I do have whatsapp downloaded on my iphone SE and when i click on it, it ask to confirm your country code and phone number. Do i do this after i get the new sim card? Then i use whatsapp like it is? The other thing is could i right now just enter my whatsapp mexico telcel number and confirm on the iphone SE that has no sim card? Thus i could use whatsapp already on my iphone SE even though it has no sim? But would i need to backup whatsapp from my iphone 4s to the SE first? Thanks.