I've never mentioned this here, but I've often wondered if someone could make a 4G radio chip dongle that would attach to the charging port and be in the form of an iPhone case. The case could have its own charging port, similar to a Mophie Juice Pack, so you could charge the phone while it was in the case. I don't think there would be a huge market for it, because it would probably cost half of what a new subsidized iPhone would cost, but it might be possible. What do you think? Do you know if the radio chip has to be in direct contact with other parts of the internal hardware in the phone?Not only does it not exist, but it's impossible. No iPhone has the hardware necessary to use a 4G network.
That's not software to convert 3G to 4G in the phone, which is what the OP asked about. MiFi is external hardware that costs $270 without a contract ($99 with a contract) and has a monthly service charge of $50. I don't know about the OP, but there's no way I'd pay for that when I'm already paying for a data plan on my phone.MIFI 4G hotspot