Can I (still) use my original iPhone by just swapping in my current 4S sim?

So long as your SIM goes into a smartphone your data plan should not change. Did you check the iPhone 2Gs SIM slot for the adapter? You probably left it in there for safe keeping.

 

^
Excellent!
I would only add you need to add to your Cydia Sources: http://cydia.pushfix.info to locate PushFix.

 

No problem.
To download the required cydia app you first need to add the repository I provided.

Without doing so you will not locate PushFix. With it added to your sources, you then will be able to.

 

I was thinking of others who would read your thread and want to do as you did. . .

 

The way I've handled this matter on the last 2 IPs (3G and IP4) was to restore the phone to factory setting. Then, set it to forward calls to a different phone number). I have one of those ATT $9.99 additional phones which I use for this.

I don't see why your method wouldn't work as well UNLESS there really is some software on the sim card that prevents using the IP 4 S sim card in another phone.

If you do go to an ATT store, I suggest you find a franchise ATT shop. The shop I use is franchised and the 2 guys that run it are VERY accommodating as to swapping sim cards in various IPs. On my IP4 S, I actually updated my additional phone (the $9.99 phone) since my IP4 was not eligible last Oct. Then before doing ANYTHING with it, I took it into the ATT shop where they did some Sim "MAGIC" and changed the new 4S to my regular number that wasn't eligible. Then they changed the sim in the IP4 to my wife's separate phone (she never had an IP before).

After trying the IP4 for about 3 weeks, she said she wanted the IP. At that time, her standard ATT ($9.99) phone was eligible for an upgrade so we got her a new IP4 S which came with a sim that had her working number.

I then retired the IP4 and sold it.

In my switch-a-roo above I did keep my unlimited plan. When the new phone comes out, I'm probably going to let the unlimited plan "sunset" as I don't see any advantage in an unlimited plan that throttles somewhere between 2 and 3 GBs and I like the concept of sharing data with all our home phones along with occasionally tethering to a laptop/tablet.

To summarize, all the sim switching was done by my friendly 2 man ATT franchise ATT store for no charge. I should note that I bought the 2 IP4 S models from them rather than Apple or ATT.com. I have no idea if a standard ATT store would be as accommodating.

 

I still have my original iPhone that I can still use as a backup to my 4S if it is down/lost. Mine was unlocked by AT&T but I was able to use my 4S's SIM card beforehand without issue (with SIM adapter).

So for now, at least where I live, you can still use the original iPhone.

Since my original iPhone is unlocked I did get a cheap T-Mobile prepaid SIM to use with it as well. It was only a few bucks on Amazon (I paid less than the actual credit on the SIM) and I only added $10. I chose the 2$ per day plan, which includes only 2G data (unlimited), text, and voice for $2 per day (if I use it for data, text, or voice in a given day--I only used about $4 on that account in the last 3 months or so).




Michael