Be sure to read this article before traveling to Iran for using your mobile phone, to be more prepared.
Locked and unlocked mobile phone are the words that you may hear on your journey, when trying to use a local SIM card on your device.
The locked mobile phone is configured to the way that you cannot insert SIM cards from other mobile providers. The unlocked mobile phone can be used in every country, so, it can be easily switched to the local mobile SIM card and benefit from using cheaper deals and services. Of course, you should know that these unlocked phones only work in Iran for 30 days. If you want to stay in Iran for more than 30 days or if you are traveling to Iran for the second time, you have to register your phone at the customs department of the international aiport.
Using the locked mobile phones will be cost an extra charge based on the roaming services of mobile operator. As a consequence, it is necessary to unlock your mobile phone by paying a fee to your mobile provider before coming to Iran.
NOTE: If you're not sure what your mobile phone status is like, you can get notified by making a call to your operator support department.

If you know that your mobile phone is locked, don't be afraid! There is a way to legally unlock your mobile and easily use your mobile forever in Iran.
Follow these below steps to get an unlocked cellphone in Iran:

NOTE: It should be noted that these sites introduced are Farsi so it is best to follow these steps with an Iranian friend.
One of the key points of preparing for a trip to any country, is to research the electrity voltage and the type of outlets. Here, you find a comprehensive guide on the types of outlets and plugs in Iran, along with the standard voltage of the electricity available to charge your devices during your trip to Iran.

سلام آقای غنی زاده هستم میخواستم تلفن همراه خود را در سامانه راجستر کنم اما انجام نمیشود
آقای غنی زاده عزیز،
سپاس از نظر شما.
اگر به صورت مهمان در ایران هستید، تا 30 روز بدون نیاز به رجیستر کردن گوشی میتوانید از آن استفاده کنید. اما اگر بیش از 30 روز اقامت دارید در ایران از طزیق سامانه همتا باید اقدام به رجیستر کردن آن کنید. آموزش ها در سایت همتا موجود هست.
“Oh! Squander not this breath that Heaven hath lent thee, Nor make too sure another breath to borrow!’” Khayam