In the U.S., it can be easier to end a marriage than to leave a loveless relationship with a cellular company. No, you don't have to move to SIM card swapping Europe. Try these guerrilla tactics to get out of your service contract.

[edit] Steps

Find an alternative Having ammunition as to what contract you are going to switch to will give you confidence and strength to go through with the painful process of getting out of your contract.
Be a squeaky wheel. Say you want out because the service isn't up to par. (And really, is it?) Then back that up by filing official complaints online with the Federal Trade Commission and the Better Business Bureau. However, if you have no grounds for complaint, then these steps will not help you.
Get a lemon. Get a known problematic phone, complain 3 times, be let out of a contract due to your local lemon law. However, most carriers and manufacturers warranty their phones for one year and will offer alternatives if you continue to have problems.
Try a market-based fix. Some companies match unhappy mobile customers with people who'd like to sign up, at a discount of course. You'll pay a $20 fee to sell your contract on the block.
Look for your provider to bury changes to Terms of Service with your bill. Quite often providers modify their service plans, much of the time the modification is a benefit. It doesn't matter, this voids the previous contract. Read the small print on those inserts included with your bill, it will spell out that you have 30 days (may vary on where you live) to cancel your contract with no charge simply because they changed the contract.
- Get off the grid. If you move and cannot get the same level of service as your previous location, tell your service provider. They're not legally required to cut you loose, but frustrated consumers have reported success. T-Mobile's and AT&T's is to waive the Early Termination Fee if you do not have service in your area. This step may have to be verified with their engineers.
- Join the army. If you are a member of the US Armed Services and you receive orders to somewhere the company doesn't provide service they are obligated to cancel your contract free of charge. Keep in mind, you'll have to provide a copy of your official orders. Your base legal office should be able to provide you with free assistance in working with the company. Most carriers will offer a military suspension option as well.
Force them to produce the signed contract. Ask them to produce a copy and mail it to you. This step rarely works anymore, as most retailers do send their paperwork to storage facilities or scan them into databases and can usually pull up contracts and receipts fairly easily.
Shrink your plan. As a last resort, cut back to the bare minimum the provider allows and drop any frills, like picture-messaging. Depending on the number of months you have left, this could be cheaper than paying the early termination fee, which can often run up to $300 per line. However, at some cellular companies changing your plan, even to reduce it, may extend it for at least another year, so do the math first to make certain it will actually save you money.
Dead?? If your cellphone happens to be in someone's name who recently deceased (spouse, Dad, Mom, the CEO/Owner of your workplace) - call and get the service cancelled.
Tethering, always fail proof. If your cellular service/cell phone allows tethering, it is rarely mentioned in the contract that there is a bandwidth limit when it comes to this. Connect to the internet using your Cell Phone 2 PC connection and set it to download as many .torrent files (or any large files) as you can, this will normally lead to deactivation of your service for an undetermined amount of time. As it normally does not state in your contract that usage can be grounds for this, it voids contract, there for letting you off.

[edit] Tips

Think carefully before you sign another contract. If you're reading this article, chances are excellent that you understand the basic nature of mobile service carriers. There are lots of alternatives that don't require contracts, and you might do well to consider one. To receive a discount on a new phone, most carriers use the contract as a sure means to make back their investment in a customer.
Consider just paying the early termination fee. Sure, it's a sock in the wallet - but once you pay, your nightmare is over. Following the steps above can be an unpleasant pursuit that spans hours, days, even weeks. What's your time worth?
If you have a contract with "Unlimited Nights and Weekends", then anything that the carrier does, or doesn't do, to limit the number of minutes you could use during that period is a potential contract violation on the carrier's part. This might work if you consistently receive 'all circuits are busy now' messages or poorer reception than advertised on their coverage maps. Plus it has the added value of being the truth.
Choose one or more these options that applies to you. Honesty is looked at with favor.
No contract is enforceable on a minor.
With SprintPCS, call customer service and ask them to use the "maintenance screen" to enable "direct mailing notification" which will notify you via text message whenever changes are made to your contract, supposedly. This seems to be the most sure-fire way of getting out with an early termination fee (with an expected amount of resistance from phone reps), but it is, of course, dependent on the company changing the contract.
Sometimes paying the early termination fee (maybe $200) is cheaper than keeping the phone and living with bad service. Especially if you have many months left in the contract and are paying for lots of minutes.
If you are with Sprint PCS, you have an automated way to request credit for a dropped call, no questions asked. Use this feature constantly. At 50 cents a pop, they are likely to want you gone if you're persistent enough. To legitimately drop enough calls. go to an area that is problematic and make as many calls as you can.

[edit] Warnings

Not all contracts provide free roaming. Make sure to check before placing a lengthy roaming call. If it's not free in your contract, it will cost you a fortune.
Some carriers will charge you a hefty Early Termination Fee if they cancel your service with "good cause", for example, if you don't pay your bill. Be aware, if you do not pay in full, you may be forwarded to a collection agency.