By the way, since I had the DVD in the computer to make the above screen grab, I watched closely to document that the phone number Dr. Floyd dials is
153-458-15445
He actually pauses that way (dials 153, pauses, dials 458, pauses again, then dials 15445).
As far as today's international numbering plan, there is no Country Code 153, and Country Code 53 is Cuba, which doesn't make sense to the context of the movie.
According to Wikipedia, Dr. Floyd (and assumedly his family) are American. I suppose the Space Station could have been part of the North American NANP, but then, despite how he paused, that would make the phone number:
1-534-581-5445
Currently, area code 534 is in Wisconsin, but there is no 581 exchange in area code 534.
For whatever reason if the Space Station was somehow a local call from the UK, 01534 is in Jersey, England.