Roll call votes
From OpenCongress Wiki
This page deals with roll call votes in the U.S. Congress. In both the House and Senate, roll call votes are defined as, “a vote on the record” in which the name of each member and his or her voting position is noted.  
How votes are called
In the House, three methods of voting are utilized for final disposition of any amendment, bill or question. These are the voice vote, the division vote, and the electronically recorded vote. A voice vote is the fastest method and is usually employed when a question is first put to the House. The presiding officer, the Chair, first calls for the “ayes” and then for the “noes,” and members shout out their vote in unison. The Chair determines the result on a comparison of the volume of ayes and noes. No individual votes or even total vote counts are recorded with this method. If it is difficult to determine the result of a voice vote, a "division" or "standing" vote may be initiated by the Chair or demanded by any member. The Chair then states: "As many as are in favor will rise and stand until counted." After counting those in favor he or she calls on those opposed to stand and be counted, thereby determining the number in favor of and those opposed to the question. Only vote totals are announced, and no individual member votes are recorded.  
A member may request a recorded vote, or roll call vote. Recorded votes have been taken by an electronic voting system on the House floor since 1973. In order for one to occur, however, the request must be supported by at least 25 members. Members usually have a minimum of 15 minutes in which to record their votes from the time the recorded vote is ordered. The Speaker may reduce the period for voting to five minutes on subsequent votes when there has been no intervening debate or business.  
In the Senate, there are also three methods of voting. These are voice vote, division, and yea and nay (roll call vote). In a voice vote, the presiding officer states the question and asks those in favor and against to say “yea” or “nay.” Once the voting has ended, he or she announces the result according to his or her judgment. The names or numbers of senators voting on each side are not recorded. A division vote requires senators to either stand or raise their hands to be counted. The chair first counts the “ayes”, then the “nays.” The numbers are not announced nor are the names recorded. A division vote is used when the results of a voice vote are in doubt.  
A roll call vote, in which both the names and positions of each voting member are recorded, may be requested by a member. The request must be seconded by 1/5 of a presumptive quorum (11 members in the Senate), but frequently the presiding officer does not bother to count; rather, he or she merely takes a glance at the showing of hands and orders the call. The names of the senators are then called in their alphabetical order. For the purpose of expedience, senators often go directly to the desk on the Senate floor and let the Clerk know their position, out of alphabetical sequence. On occasion, senators simply give a hand signal (thumbs up or down) to the clerk rather than approach the desk or wait for their name to be called in order.