What is the ruling on setting the Eid takbir, the Meccan adhan, or supplications as a mobile phone ringtone, knowing that the ringtone stops upon answering, and is this considered unlawful?

There is no harm in using the adhan (call to prayer) or du'a (supplication) as a ringtone for mobile calls, unless it leads to a forbidden religious act, such as ridiculing the rituals of Allah. One should silence the mobile phone when entering the restroom to avoid hearing the remembrance of Allah in that place. Stopping the adhan or du'a from playing is neither obligatory nor forbidden.