Methods and devices are provided for disambiguating the timing of uplink transmissions. In one embodiment, the method may involve receiving from a wireless network a global time value having a wraparound time longer than that of a system frame number for the network, the global time value being based at least in part on an overhead message conveying at least one parameter of a first radio access technology (RAT) different from a second RAT used by the network. The method may involve determining a current global time based on the received global time value, and sending an uplink message that includes the current global time as a global timestamp.