在S60第二版中，SIP并不是平台的一部分，但可以作为S60第二版SDK的一个补充来使用，而在S60第三版中SIP API是继承在平台中的。



代码的不兼容使得开发者开发一个支持所有设备的SIP客户端程序显得有些复杂，实际开发时，开发者需要根据不同的平台下进行条件编译，因此要维护不同版本的代码。-In the second edition of S60, SIP is not part of the platform, but the S60 2nd Edition SDK can be used as a supplement to use, and in the S60 third edition of the SIP API is inherited in the Platform. Not compatible with the code allows developers to support all the equipment to develop a SIP client program seems a bit complicated, the actual development, developers need to carry out under different conditions of platform compilation, so to maintain different versions of the code.