Question: In a PSS session with multiple media components sharing a single QoS reservation (PDP context), when should the '3GPP-Link-Char' header be sent, and what type of URI should be used in its specification?
Option 1: Before SETUP request, with individual media stream URIs.
Option 2: After PLAY request, with an aggregated SP URI.
Option 3: During OPTIONS request, with either absolute or relative URIs for each media component.
Option 4: Before SET_PARAMETER request, with a mix of individual and aggregate URIs.
Explanation: According to the specifications, if a QoS reservation (PDP context) is shared by several media components in a session, the '3GPP-Link-Char' header should not be sent prior to the SP PLAY request. In this scenario, the correct approach is to send the header after the PLAY request, using an aggregated SP URI to apply the link characteristics to all media components sharing the QoS reservation.