Cell Phone dilemma

I have the oldest cell phone in the Eastern United States. Okay, maybe it's not the oldest, but it's got to be close. It's a Verizon LG, and it's about 4 years old. In fact, I've had several people tell me "I had that phone three phones ago!"

I'm not crazy about it, either. It works fine, save for two major complaints:
1. There's an external button that cycles the phone between Normal, Vibrate, and Silent. On a daily basis, the phone squeezes against my keys or something in my pocket and turns itself silent, so that I'll miss all future calls.
2. The ringer doesn't get very loud. I've missed dozens of calls simply because I didn't hear it. In addition, "ring+vibrate" mode has never worked, so at all times I have to risk either not hearing it ring, or not feeling it vibrate.

On the other hand, it does everything I need it to. It's tri-band, so I'm rarely without signal -- although our house is in a signal-weak spot, so it's hard to use at home. I set up the one-touch favorite button to open up the calculator, which I use frequently. And although it's been through a lot over four years, including several drops, it still works. It's also my primary phone book (I know it's a bad idea not to have a backup...)

So here's my dilemma: I'm ready for a new phone. Verizon would be happy to give me a free phone, in return for re-upping my contract. However, it appears that they've discontinued our 500-minute family plan, so we'd probably have to move up to their current "base" plan, $10 more per month. This, even though we've never once exceeded our 500 minute monthly allowance.

I have no particular loyalty to Verizon, and I'm thoroughly won over by the iPhone, which is only available through AT&T. With wireless number portability, I could keep my number and move to any other issuer.

But here's the catch: There's a reasonable possibility that my next employer will require me to carry a company cell phone, blackberry, etc. Rather than carry two phones (been there, done that), I'd much rather have them pick up the bill for my existing wireless number. But not knowing who my next employer will be, I also don't know which wireless carrier they will use. I don't want to sign a 2-year contract with AT&T, and within a few weeks (or months) be told that I need to carry a company phone that's on the Verizon network. That would leave me the choices of (a) swallow an exorbitant cancellation fee to get out of my contract, or (b) go back to carrying two cell phones - my own, and the company's.

This is all to say: In addition to everything else, getting a new wireless phone is one of the many things that are dependent upon finding a job. Until then, old LG, please hold out!