This read-create enumerated value sets the data rate carried by each allocated time slot on the FT1 interface, either nx56kbps or nx64kbps, defaulting to nx64kbps. An admin chooses nx56kbps when the carrier circuit only supports robbed-bit signaling that reserves a bit per channel for signaling, and nx64kbps for clear-channel DS0s, since a mismatch here would misalign the bandwidth budget of the interface. For example, setting rsFt1IfTimeSlotRate to nx56kbps(0) configures each allocated DS0 to carry 56 kbps of usable payload instead of the full 64 kbps.