How-to: Switch to T-Mobile from AT&T because you are miserly.
Step 1. Let your 2 year contract with AT&T expire. Woohoo! Now that iPhone 3G is yours free and clear. Now, make sure you resist the tempation to re-up the contract in order to buy a fancy schmancy iPhone 4.
Step 2. Get laid-off and cancel your iPhone data service to save $30/month. (I know this is a tough step to follow, but trust me on this, it’s going to be worth it). Use your old crappy phone for a while.
Step 3. Get sick of not having enough minutes with the AT&T 700 minutes for $70/month 2 line plan. Decide to drop “those bums” and start shopping for a different plan. Make a spreadsheet.
Step 4. Realize that your current phones are GSM and that means you can switch to T-Mobile if you can manage to unlock them. Do research. Figure out that unlocking an iPhone is usually trivial. Find out that unlocking a Motorola L2 SLVR is not trivial, but is still definitely possible.
Step 5. Sign up for the 1500 minutes for $60/month plan at T-Mobile, ask for just the SIM cards and transfer your old numbers (remember to bring in your AT&T account number). Unlock your phone and your wife’s phone. Bonus points for backing up her phone book and not bricking her phone, I recommend using P2KTools. Pop in the new SIM. Disable cellular data on your iPhone (you cheapskate) you will just use wifi hotspots from now on. Within 24 hours both phones will be up and running on the old number with the shiny new minutes ready to be used up.
That’s it!