Receiving calls from Iridium should be free – the caller usually pays for the satellite portion of the call.
That usually makes Iridium -> terrestrial calls much more economical than the other way around, as telcos usually use the opportunity of terrestrial -> satcom calls to add on ridiculous margins. Conversely, satellite -> terrestrial calling is usually around a dollar per minute or less, these days.
In your situation, that would come out to a $50 (or maybe $25) charge per minute. Hefty, but that indeed seems to be at least in the ballpark of their listed rates (for prepaid here, for example: https://prepaid.t-mobile.com/connect/international-calling-r...).
That usually makes Iridium -> terrestrial calls much more economical than the other way around, as telcos usually use the opportunity of terrestrial -> satcom calls to add on ridiculous margins. Conversely, satellite -> terrestrial calling is usually around a dollar per minute or less, these days.
In your situation, that would come out to a $50 (or maybe $25) charge per minute. Hefty, but that indeed seems to be at least in the ballpark of their listed rates (for prepaid here, for example: https://prepaid.t-mobile.com/connect/international-calling-r...).