911 and 411 work from nearly every telephone in the U.S. and Canada, while the others vary from place to place. Generally, only 4-1-1 calls incur a toll. 911 access is mandated by law, even on lines with no service (a "soft" dial tone). 6-1-1 (formerly 8-1-1) may also be accessible to activate service on such lines, and 3-1-1 may be available as well for urgent (but non-emergency) calls to police, or any call to local government in some places.
Other community services are provided through 2-1-1, but only if a non-profit organization such as the United Way operates it locally. Likewise, local or state/provincial government may or may not operate traffic information through 5-1-1. 8-1-1 will be mandatory in the U.S. in 2007, as 7-1-1 is now. Unlike 9-1-1, these may or may not be available on a phone without paid service.
0-1-1 followed by a country code is used to dial internationally, but this use is not considered an N11 code. 1-1-1 is not available in the NANP, because 11 is the prefix used to access vertical service codes from rotary phones, and is essentially meaningless to the system otherwise.
