When an old phone at AT&T is no longer wanted for any reason—such as technical problems, personal preferences, an outdated phone, or even when a newer model is no longer wanted—switching to a different phone becomes a consideration. Depending on the length of the contract remaining on the phone, AT&T has these two basic options to switch the phone: upgrade to a new phone or buy a new phone.
View your AT&T account online, or visit an AT&T store and talk to a representative. When switching to a new phone, first determine if your current phone is eligible for an upgrade. Upgrading will save money, because you can get the phone you want at a lower cost and take advantage of any deals or promotions. According to AT&T's website, upgrades are available every 20 months.
Buy a new phone. When upgrading, discounts are available and the phone automatically keeps the original number. If an upgrade is not available, purchase the phone you want, and inform the representative that you prefer to keep the number from your old phone.
Put the old SIM card into the new phone if necessary. The SIM card might need to be transferred to the new phone, but some phones will require a new SIM card to obtain services. The store representative will determine if putting the old SIM card in the new phone is available. This is an option when the phone is purchased to switch rather than upgraded.
Activate the phone. The phone is activated at the time of the upgrade or purchase, usually via the in-store representatives. If the phone was purchased online, you choose not to activate it or the phone is not working properly after activation, call customer service and request activation or help in troubleshooting.