Well by using the payphone or a calling card there still a chance of being traced, because you had to purchase the calling card at a " physical store" unless you buy them online, although by doing this your IP is captured {unless you spoof your IP which is very simple} and you may also need a cc to purchase a calling card so there is still a link not counting that you still have to use a telephone to use this calling card, then if you use a payphone chances are somebody have seen you, or the lense of a survellaince camera have captured you. In regards to the spoofcard same thing as a calling card "a link to a physical connection is needed". and we this 2 methods you cant change the cname unless you use the other thing but will not help you with the ANI.
I think the VOIP thing is the closest to "remain unknown"
VoipHead - Xhacker