vcf2PHASE stops at "Reading in VCF..."

I am trying to use vcf2PHASE.pl to convert a vcf file to a fastPHASE file. The program stalls at "Reading in VCF...". I would like more information about the VCF that the script can take. Is there a limit to amount of loci/ individuals? Does the VCF need to be phased? Can the vcf be zipped? More documentation would be great!
Thanks