Is Your Sony ST21i works only with one sim card ?
This is mean that Your Sony ST21i is locked (simlock) and can be use only with sim card from network You bought it.

If You like to use Your ST21i with other sim cards (if Your phone uses Vodafone and You wish to use Orange) You need to unlock it.

Sim-unlock.net is specialising in fast and easy phone unlocking. We are using the latest unlocking technology, that's why the unlocking with us save time and problems.
You don't need any special skills or knowledge to unlock Your ST21i .

So Your Sony ST21i is locked and You can't use it with all sim cards?

You can unlock it now.

We offert permanent unlocking solution done directly through Sony database.

We can unlock Your Sony ST21i from AT&t, T-mobile, Orange, O2, Vodafone and all worldwide networks.

To order an unlock code for Sony ST21i You need to :

1. go to sim-unlock.net and choose Your Sony model or go directly to unlock by code Sony ST21i
2. press "Unlock Sony ST21i"
3. Choose unlock product for Your Sony ( in some cases only one product is available )
4. Enter your Sony IMEI number and if needed other required information.
5. press "order code"
6. at shopping cart fill all needed information like name, e-mail and others
7. Pay for an unlock code
8. after average time (check how much it takes for chosen product) You will receive all codes and unlock guide to Your Sony ST21i .

Easy way to enter unlock code to Sony ST21i :

For Sony ST21i, You need to power Your ST21i on with unaccepted SIM card, wait for a few seconds until the phone asks for a
network unlock pin code. When you see the message, enter the code received from Us.

After unlock Your Sony ST21i You can use it with any sim card.
Try sim-unlock.net whitout any fear.
Unlocking also allow You to increase value of your Sony ST21i because it can be used with all network cards.
Unlock code will be sent to email, and your Sony will be permanently Unlocked to work on any GSM Carrier, and you can use any sim card operators such as Movistar, Rogers, O2, Orange, T-mobile, Vodafone, Telenor, Telia, Hutchison, Telenor etc.

Why unlock Sony ST21i and why choose sim-unlock.net ?
- our support will answer to Your question and problems while unlocking Sony ST21i
- opportunity to buy a foreign SIM card in another country to avoid roaming charges
- after unlock You can take advantage of cheaper tariffs from locally competing networks while abroad
- waiting time for the code was reduced to a minimum by an automated system on our website
- we always inform You how to enter unlock code to Your Sony
- we are cheapest unlocking site over the internet

See More: How to fast unlock Sony ST21i by code to use all sim card Sony unlock