What is * 3370 on iPhone?

Have you ever heard of the function * 3370 on your iPhone? This feature is actually hidden and not many people know about it. In this article, we will explain what * 3370 is and how it can benefit you.

What is * 3370 on iPhone?

* 3370 is a code that allows you to activate Enhanced Full Rate (EFR) on your iPhone. EFR is a speech coding algorithm that is used to improve the quality of voice calls. This feature is not enabled by default on all iPhones, but can be activated by dialing * 3370.

When EFR is enabled, it compresses the audio during a call to minimize the amount of data being transmitted. This results in a clearer and crisper call quality, especially in areas with poor network coverage.

How to use * 3370 on iPhone?

To activate EFR on your iPhone, simply dial * 3370 and press the call button. Your iPhone will then restart automatically. Once your phone has restarted, EFR will be activated and you can enjoy better call quality.

It is important to note that enabling EFR may increase battery consumption, as the phone needs to compress and decompress the audio data during a call. However, the difference is usually minimal and should not cause any significant battery drain.

Benefits of using * 3370 on iPhone

There are several benefits to using * 3370 on your iPhone:

  • Better call quality in areas with poor network coverage.
  • Crisper and clearer audio during voice calls.
  • Enhanced Full Rate (EFR) reduces background noise during a call.

Disadvantages of using * 3370 on iPhone

While there are many advantages to using * 3370 on your iPhone, it is important to consider the potential disadvantages as well:

  • Enabling EFR may increase battery consumption.
  • Not all carriers support EFR, so it may not work in all areas.


* 3370 is a useful feature on iPhones that can improve call quality by activating Enhanced Full Rate (EFR) speech coding. While it may have some potential drawbacks, the benefits of using * 3370 outweigh them. So why not give it a try and see if you notice the difference?

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