ISO/IEC 22535:2009规定了在企业电信网络(CN)内通过会话发起协议(SIP)进行“QSIG”的隧道传输。通过采用SIP的公共IP网络的QSIG隧道超出了ISO/IEC 22535:2009的范围。然而，当与其他相关功能（例如，地址转换、安全功能等）结合部署时，本国际标准中规定的功能原则上适用于这种情况。）。ISO/IEC 22535:2009适用于可以充当采用QSIG的PISN和采用SIP的公司IP网络之间的网关的任何互通单元，其中QSIG在SIP请求和响应中通过隧道传输。

ISO/IEC 22535:2009 specifies tunnelling of "QSIG" over the Session Initiation Protocol (SIP) within a corporate telecommunication network (CN).

The tunnelling of QSIG through a public IP network employing SIP is outside the scope of ISO/IEC 22535:2009. However, the functionality specified in this International Standard is in principle applicable to such a scenario when deployed in conjunction with other relevant functionality (e.g. address translation, security functions, etc.).

ISO/IEC 22535:2009 is applicable to any interworking unit that can act as a gateway between a PISN employing QSIG and a corporate IP network employing SIP, with QSIG tunnelled within SIP requests and responses.