You should be OK with that, here is the recomended Drives direct from the documentation.
Tape drive requirements
Depending on the software release and type of hardware platform, the
Meridian Mail system uses one of the following tape drives and tapes:
Tape drive Tape Migration use
Archive Viper 250 Mbyte No
Tandberg SLR4 tape drive (TDC4220) 2.5 Gbyte Yes
.
CAUTION
Risk of migration failure
The CallPilot server uses a tape drive that cannot read data
from 250 MByte tapes and tapes created with the Archive
Viper tape drive.
You must use a Tandberg SLR4 (or later) tape drive
and 2.5 Gbyte tapes to create the Meridian Mail migration
tapes.
ATTENTION If the Meridian Mail system to be migrated uses an Archive
Viper tape drive or 250 Mbyte tapes, ensure that you take
to the customer site a Tandberg SLR4 (TDC4220) tape
drive and a supply of 2.5 Gbyte tapes.
It's a phone system, NOT a clock!