Warning: the last version of 3GPP TS 24.228 is v5.15, published in October 2006. It has not been upgraded to Rel-6 and the following note has been added to the scope of the document:
The detailed signalling flows in the present document can be referenced, but the specification will not be
further maintained. The example flows can contain errors and can only be regarded as guidelines for
persons wanting an overview of how SIP messages with detailed header information could in some
example cases look like within 3GPP. Other not documented signalling flows can be as relevant and
compliant as the ones that are outlined in this specification.