The main goal of restoring the iOS device is to reset its factory settings with an increase in the software version (IOS firmware). Refractive (recovery) is usually performed with:
- the presence of the software failure of the iOS device;
- in order to install the last software;
- To create a "clean system" (for example, when changing the host of the device or for the purpose of the subsequent jailbreak).

In the process of iOS update, data (applications, photos, contacts, etc.) on the iOS device are saved. When restoring the device will receive "factory settings" (clean system), while all user data will be deleted.

- Never use the update on the device with jailbreak! Often this leads to the "eternal chamomile" or "loop" in recovery mode (Recovery Mode, iTunes icon on the screen). A jailbreak device is recommended to restore from DFU MODE.

- Never use the update or restore to the official iOS firmware on the locked iPhone. When updating or recovery, along with iOS firmware, the firmware firmware firmware is also enhanced, which will lead to the impossibility of its unlock by the programmate. In this case, it is necessary to use the restoration to the custom firmware without increasing the modem. Read more about it here.

1. In iTunes by clicking on the Update button.

2. "By air" directly on the device with the availability of the Internet. For Go to Settings ->Major ->Software Update.

First of all, when you make an order in the store, ask the seller from where the iPhone is imported.
Take care of the SIM card to check the iPhone. If you do not have a micro sim (for iPhone 4S) or Nano Sim (for iPhone 5 and above), then check the phone for the ability to make calls will not work.

As a rule, the cheapest devices are phones from the showcase or replaced by the previous buyers. Whether the iPhone was replaced by IMEI (references at the end of the review). Carefully examine the box, look for protective films in place without air bubbles under them.

Here is what you need to learn about your new phone:
- The country from which it was imported by the iPhone.
- The correspondence of the fact that in the room printed on the box with the fact that inside the box.
- Well, the option when the model cannot determine the dishtop of the device from the operator. Check iPhone by IMEI.
Basic phone data can be found without opening the packaging. On the back of the box will be a sticker with barcodes with data about iPhone.
We are interested in:
1 model number
2 serial number
3 IMEI number

The same information can be obtained by turning on the phone and launching the “Settings” application. In the “Major” menu>“About the device“.
Check if the numbers shown on the box and in the phone settings match. If not, then it is likely that this device has been in the warranty workshop.
If the serial number starts at 5K, then this is the unit restored at the factory.

By model number, you can find out from which country the iPhone was brought.
The letters after the numbers to the “/” mark indicate the region of sale and warranty service.
For example MC131TA / A - IPhone 3G 16GB Black, purchased in Taiwan (Chunghwa Telecom)
The official Russian phone (PCT) numbers are:
MB489RS / A, MB496RS / A, MB500RS / A, MC131RS / A, MC132RS / A, MC133RS / A, MC134RS / A
Check on iPhoneFrom.com .

AB (AE) - AOE (Etisalat and DU operators unlocked)
AB - Egypt, Jordan (operators Vodafone and Orange, blocked)
AE - Saudi Arabia (Mobily and Support operator unlocked)
B - United Kingdom and Ireland (O2 operator, blocked)
BZ - Brazil (CLARO, VIVO operator, blocked)
C - Canada (FIDO and ROGERS operators blocked)
CZ (CS) - Czech Republic (O2, T-Mobile, Vodafone operators, unlocked)
DN - Austria, Germany, Netherlands (T-Mobile operator, blocked)
E - Mexico (Telcel operator, blocked)
EE - Estonia (EMT operator, blocked)
ER - Ireland (unlocked)
FB - Luxembourg (operators: LUXGSM; Tango - unlocked);
FB - France (Orange, Bouygues, SFR operator is blocked, but with the ability to remove the SIM-Loca on additional conditions) an exception is an iPhone 4 (4S) when you buy an Apple Store (operator it will be blocked)
FD - Austria, Liechtenstein, Switzerland (Operators One, Orange, SwissCom, blocked)
GR - Greece (Vodafone operator, unlocked)
HB - Israel (Cellcom, Orange and Pelephone operators, blocked, but with the ability to remove the SIM-Loca on additional conditions)
HN - India (Airtel and Vodafone operators, blocked)
IP - Italy - blocked
J - Japan (Softbank operator, blocked)
KN - Denmark and Norway (Telia and Netccom operators, blocked)
KS - Finland and Sweden (Telia, Sonera operators, blocked)
KH - China (CHINA Unicom operator, unlocked)
KH - Korea (CHINA Unicom operator, blocked)
La - Guatemala, Honduras, Columbia, Peru, Salvador, Ecuador (COMCEL, CLARO, MOVISTAR, PORTA, TM SAC, Blocked)
Le - Argentina (CLARO, MOVISTAR operators, blocked)
LL - USA (AT & T operator, blocked)
Lt - Lithuania (Omnitel operator, blocked)
LV - Latvia (LMT operator, blocked)
LZ - Paraguay, Chile, Uruguay (CTI MOVIL, CLARO, MOVISTAR, TMC operators, blocked)
MG - Hungary (T-Mobile operator, blocked)
NF - Belgium, France (operators Mobistar and Orange, blocked)
NF - Luxembourg (VOX Mobile operator unlocked)
PL - POLAND (ERA and ORANGE operators, blocked)
PO - Portugal (Optimus and Vodafone operators, blocked)
PP - Philippines (Globe operator, blocked)
RO - Romania (Orange operator, blocked)
RS (RR) - Russia (Vimpelcom, Megafon, MTS, unlocked)
RR - Moldova (ORANGE operator, blocked)
SL - Slovakia (Orange operators unlocked)
SO - South Africa (Vodacom operators unlocked)
T - Italy (Tim and Vodafone operator, unlocked)
TA - Taiwan (CHUNGHWA Telecom operator, unlocked)
TU - Turkey (Vodafone operator is blocked)
TU - Turkey (Turkcell operator unlocked)
X - Australia (Optus, Telstra, Vodafone operators, blocked)
X - New Zealand (Vodafone operator, unlocked)
Y - Spain (operator MOVISTAR, blocked)
ZA - Singapore (Singtel operator, unlocked)
ZP - Hong Kong and Macau (Operator Three, unlocked)

The serial number provides significantly more information.
These are 11 signs on which you can find out the device model, color, date of manufacture.
Whether the device is activated, and if the iPhone is on warranty.
The information obtained can immediately verify with what you have in your hands.
Specifications of this iPhone can be checked on chipmunk chipmunk.nl website

Most of all information about the device can be obtained by IMEI (INTERNATIONAL MOBILE EQUIPMENT IDENTITY - 15 digits).
By the way, you can find it just typing on the keyboard: * # 06 #
In addition to all the information that is available when checking the serial number, IMEI can still find out the anlok status for the iPhone. Those. Ability to operate the phone with any cellular operator.
On this site you can get the specifications of the iPhone Sndeep.info/en

Check it on the following sites:
iunlocker.net

By the way, pay attention.
This site provides information on replaced devices.
Sometimes sellers offer phones that buyers returned for various reasons. Perhaps there is nothing terrible in this, but as a rule, the appearance of such an iPhone can be a bit taken back and as a gift they definitely do not fit.

Second site:
http://unlockpro.ru/check_imei/

The support service is even working here, which if necessary, can unlock your iPhone for money.
Information about whether the phone is unlocked, you can also find out on this page:http://www.iphone-gps.ru/imei/

For the first time, the Activation Lock feature appeared in the iOS 7 operating system and as of December last year, it is activated on 78% of all iPhones. After its appearance, the level of thefts of the iPhone and iPad has noticeably decreased.

You can check the iPhone on the iCloud.com websitehttps://www.icloud.com/activationlock/.To check the status of the Activation Lock function, you must enter into the IMEI form or the serial number of the mobile device, as well as captcha (a set of letters and characters to protect against bots). This will avoid buying a device that has already been blocked by the previous owner. In case the Activation Lock function is enabled, you must ask the seller to disable it, which will require an Apple ID and password from it

You can find out the serial number of your device in several ways. The easiest way is to look into the settings of your iPhone or iPad. To do this, run the application "Settings" and go to "Basic">"On this device", where in the general list we are looking for a cherished line "serial number".

If you have somewhere nearby lies the box from the mobile device, take a look at it. Information about the serial number should be signed on the sticker located on the back of the box.

If for some reason the box is not survived, and the device screen does not work, use the iTunes program. To do this, the device must be connected to a computer and, running on iTunes PC, go to the "Overview" section.

Also, the serial number can be engraved on the device itself itself. However, you can find this information only from the iPad and iPod Touch.

After you have found the serial number of your mobile device, before moving to its decryption, you must count the number of characters in combination. Not so long ago, Apple used 11-digit serial numbers, but since 2010 the company began to switch to 12-digit. At the same time, the structure of such numbers differs, which is important to consider when trying to decipher.

The structure of the 11-digit serial looks as follows:

• The first two signs are the identifier of the unit, roughly speaking, the workshop number;
  
• The third character is the last digit of the year the device was manufactured. For example, if the phone was released in 2010 - it will be 0, if in 2011 - 1, in 2012 - 2 and so on;
  
• The following two red signs are a week of production. I have this "08" - the eighth week of 2011, that is February;
  
• From the sixth eighth sign - the code of the iPhone number in this party, for 8 week of 2011. I have it "4cq";
  
• Two signs following it, enclosed in an orange square, designate the model and its color;
  
• Well, the last character (in yellow) indicates the amount of memory device.

In this, Cupertinovtsy uses 12-digit serial numbers, like this:

Such serial numbers have the following structure:

• The first three signs are the code of the division. All iPhone, iPad and iPod Touch are produced at the Foxconn Giant Plant in the PRC. This company has many units and, unfortunately, there is no complete list of values ​​of the combination of these signs, except for Apple;
  
• the fourth character is the half year code in which the device is released;
  
• the fifth digit is the release week code, the countdown starting from the beginning of the half year, which is encrypted by the fourth digit;
  
• from 6 to 8 digits - unique for each device code
  
• the last four characters are the model code, which reports information about the generation, memory size, color of the model, and so on.