WI-FI connection is present in many hotels, but there are still signal-quality concerns. If you have contacted a local guide, you can ask him to buy an Iranian data sim and put it in one of your devices. In this way you will have the data network more or less in all cities, although during long journeys in virtually desert areas the coverage will be much lower.
In case you expect to make/receive several calls to/from your country, our advice is to subscribe (if present) one of your country operator options for international calls.