The correct action here is to silent the phone. If the phone is in your pocket, you can quickly reach it with one hand and silent the phone. If it is on the floor, you can quickly pick it up and silent it and continue your prayer. During this time you should not act as if you are breaking the salat. Your intentions should simply be to fix the problem which in this case is the ringing of phone. By doing so you are doing a big favour to Jammat who can be easily distracted by the ringing tone, including the Imam.
What Movement Breaks the Salat
Moving one hand in prayer does not break the salat. Common example is one is standing while in prayer but he has an urge for itching, he can itch his beard for example. It does not break the payer. This is called Amal Qaleel.
Moving both hands from its normal place is called Amal Katheer. This makes the prayer invalid. A more proper definition is, if an onlooker sees you from a distance and he is convinced that he is not in Salat, this is Amal Katheer.
If you are moving one hand only, make sure that the moment is short enough. If one can recite (سبحان ربي الأعلى) three times during this movement (one hand only), it become Amal Khateer. Also not that if you are moving one hand (for example itching) repeatedly. Try to create a gap in your action. If you are doing thee consecutive action, and you cannot recite (سبحان ربي الأعلى) three times in these gaps, this also become Amal Khatheer.
My opinion is, even if the phone is on the floor, one can quickly focus on it, pick it and silent it. While this does involve the whole body movement, the onlooker can easy guess that he is trying to fix a problem and not really breaking the Salat.
Link 1, Link 2