copying.txt

a file about net phone based on IP,write by VC++.

                                   GNU GENERAL PUBLIC LICENSE
                                       Version 2, June 1991 

              Copyright (C) 1989, 1991 Free Software Foundation, Inc.
              675 Mass Ave, Cambridge, MA 02139, USA
              Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is
              not allowed. 

                                          Preamble 

              The licenses for most software are designed to take away your freedom to share and change it. By
              contrast, the GNU General Public License is intended to guarantee your freedom to share and change
              free software--to make sure the software is free for all its users. This General Public License applies to
              most of the Free Software Foundation's software and to any other program whose authors commit to
              using it. (Some other Free Software Foundation software is covered by the GNU Library General
              Public License instead.) You can apply it to your programs, too. 

              When we speak of free software, we are referring to freedom, not price. Our General Public Licenses
              are designed to make sure that you have the freedom to distribute copies of free software (and charge
              for this service if you wish), that you receive source code or can get it if you want it, that you can change
              the software or use pieces of it in new free programs; and that you know you can do these things. 

              To protect your rights, we need to make restrictions that forbid anyone to deny you these rights or to
              ask you to surrender the rights. These restrictions translate to certain responsibilities for you if you
              distribute copies of the software, or if you modify it. 

              For example, if you distribute copies of such a program, whether gratis or for a fee, you must give the
              recipients all the rights that you have. You must make sure that they, too, receive or can get the source
              code. And you must show them these terms so they know their rights. 

              We protect your rights with two steps: (1) copyright the software, and (2) offer you this license which
              gives you legal permission to copy, distribute and/or modify the software. 

              Also, for each author's protection and ours, we want to make certain that everyone understands that
              there is no warranty for this free software. If the software is modified by someone else and passed on,
              we want its recipients to know that what they have is not the original, so that any problems introduced
              by others will not reflect on the original authors' reputations. 

              Finally, any free program is threatened constantly by software patents. We wish to avoid the danger that
              redistributors of a free program will individually obtain patent licenses, in effect making the program
              proprietary. To prevent this, we have made it clear that any patent must be licensed for everyone's free
              use or not licensed at all. 

              The precise terms and conditions for copying, distribution and modification follow. 
                  GNU GENERAL PUBLIC LICENSE TERMS AND CONDITIONS FOR COPYING,
                                DISTRIBUTION AND MODIFICATION 

              0. This License applies to any program or other work which contains a notice placed by the copyright
              holder saying it may be distributed under the terms of this General Public License. The "Program",
              below, refers to any such program or work, and a "work based on the Program" means either the
              Program or any derivative work under copyright law: that is to say, a work containing the Program or a
              portion of it, either verbatim or with modifications and/or translated into another language. (Hereinafter,
              translation is included without limitation in the term "modification".) Each licensee is addressed as "you". 

              Activities other than copying, distribution and modification are not covered by this License; they are
              outside its scope. The act of running the Program is not restricted, and the output from the Program is
              covered only if its contents constitute a work based on the Program (independent of having been made
              by running the Program). Whether that is true depends on what the Program does. 

              1. You may copy and distribute verbatim copies of the Program's source code as you receive it, in any
              medium, provided that you conspicuously and appropriately publish on each copy an appropriate
              copyright notice and disclaimer of warranty; keep intact all the notices that refer to this License and to
              the absence of any warranty; and give any other recipients of the Program a copy of this License along
              with the Program. 

              You may charge a fee for the physical act of transferring a copy, and you may at your option offer
              warranty protection in exchange for a fee. 

              2. You may modify your copy or copies of the Program or any portion of it, thus forming a work based
              on the Program, and copy and distribute such modifications or work under the terms of Section 1
              above, provided that you also meet all of these conditions: 

                  a) You must cause the modified files to carry prominent notices stating that you changed
                  the files and the date of any change. 

                  b) You must cause any work that you distribute or publish, that in whole or in part contains
                  or is derived from the Program or any part thereof, to be licensed as a whole at no charge
                  to all third parties under the terms of this License. 

                  c) If the modified program normally reads commands interactively when run, you must
                  cause it, when started running for such interactive use in the most ordinary way, to print or
                  display an announcement including an appropriate copyright notice and a notice that there
                  is no warranty (or else, saying that you provide a warranty) and that users may redistribute
                  the program under these conditions, and telling the user how to view a copy of this
                  License. (Exception: if the Program itself is interactive but does not normally print such an
                  announcement, your work based on the Program is not required to print an
                  announcement.) 

              These requirements apply to the modified work as a whole. If identifiable sections of that work are not
              derived from the Program, and can be reasonably considered independent and separate works in
              themselves, then this License, and its terms, do not apply to those sections when you distribute them as
              separate works. But when you distribute the same sections as part of a whole which is a work based on
              the Program, the distribution of the whole must be on the terms of this License, whose permissions for
              other licensees extend to the entire whole, and thus to each and every part regardless of who wrote it.
              Thus, it is not the intent of this section to claim rights or contest your rights to work written entirely by
              you; rather, the intent is to exercise the right to control the distribution of derivative or collective works
              based on the Program. 

              In addition, mere aggregation of another work not based on the Program with the Program (or with a
              work based on the Program) on a volume of a storage or distribution medium does not bring the other
              work under the scope of this License. 

              3. You may copy and distribute the Program (or a work based on it, under Section 2) in object code or
              executable form under the terms of Sections 1 and 2 above provided that you also do one of the
              following: 

                  a) Accompany it with the complete corresponding machine-readable source code, which
                  must be distributed under the terms of Sections 1 and 2 above on a medium customarily
                  used for software interchange; or,