It is disliked to use the cell phone while performing Tawaf. A Muslim should avoid such an action to prevent any confusion, since using the cell phone can disrupt and confuse others and is tantamount to desecrating the ritual itself.
The prominent Muslim scholar Dr. `Ugail An-Nashmi, former Head of the Faculty of Shari`ah in Kuwait, issues the following fatwa: Muslim jurists agree that it is permissible to engage in talking during Tawaf if there is some important reason for doing so. However, if there is no need to talk, then it is considered makruh. Scholars say that it is recommended to avoid talking while performing Tawaf, unless there is a need to do that. At-Tirmidhi reported that the Prophet (peace and blessings be upon him) said: “Tawaf is just like Prayer. The only one difference is that you can talk in it. If anyone of you needs to talk, let him say what is good.” Based on this, talking without necessity is considered reprehensible. This includes talking on the cellular. In addition, using the cell phone belittles the greatness of this ritual of Tawaf; such belittling should be avoided in this holy place.
Besides, we should shut the door that leads to troubles and confusion because by raising one’s voice while talking on the phone, one causes troubles to others who are engaged in supplication and prayer.