  Devices with multiple Subscriber Identification Modules (SIM)s are expected
to prevail over the conventional devices with only one SIM. Despite the growing
demand for such devices, only proprietary solutions are available so far. To
fill this gap, the Third Generation Partnership Project (3GPP) is aiming at the
development of unified cross-platform solutions for multi-SIM device
coordination. This paper extends the technical discussion and investigation of
the 3GPP solutions for improving mobile Terminated (MT) service delivery to
multi-SIM devices. Implementation trade-offs, impact on the Quality of
Service(QoS), and possible future directions in 3GPP are outlined.
