Question: In WB-S1 mode, how can a UE request the dedicated EPS bearer context activation procedure?
Option 1: By sending a TRACKING AREA UPDATE REQUEST message.
Option 2: By means of the UE requested bearer resource allocation procedure or the UE requested bearer resource modification procedure.
Option 3: By initiating the default EPS bearer context activation procedure.
Option 4: By sending a SERVICE REQUEST message.
Explanation: In WB-S1 mode, the dedicated EPS bearer context activation procedure can be initiated by the network, but it can also be requested by the UE through specific procedures. The correct answer is option 2, which states that the UE can request the dedicated EPS bearer context activation procedure by means of the UE requested bearer resource allocation procedure or the UE requested bearer resource modification procedure, as specified in clauses 6.5.3 and 6.5.4 respectively.