Yes, it's like a regular PRI. You'll need three TA908e units as each one can provide a maximum of two PRIs. You will need to be careful with the timing source (clock). If the PBX uses a common clock for all PRIs as is typical, you'll likely want the PBX to provide clock and have the TA908e units use the PBX's T-1s as clock source. The provider on the other end of the fiber will need to provide hunt (series completion) on the SIP trunks feeding the three units to roll over to the next if one is busy. Other than those considerations it's pretty much a by-the-book setup.