Archived from groups: alt.cellular.fido (More info?)
GSM phones being sold by different providers are normally locked to
their networks only. A Fido phone that is locked cannot be used with a
another SIM card from, say, Rogers or other GSM providers. It will have
to be unlocked to be able to use other providers SIM - thus allowing it
to be used in that other providers' networks.
You will not get unlimited time when you unlock your phone but it gives
you the freedom to use your cell phone with other providers' SIM.