I think you might need to change your outbound dial plan to allow these calls. Currently anything that starts with *75 activates an Obi function. Optionally you might be able to just change the line 22 star code from
*75([1-9]|[1-9]x), Check Speed Dial, say($Spd[$Code])
to
*99([1-9]|[1-9]x), Check Speed Dial, say($Spd[$Code])
Edit: The topic you pointed out is the same problem with a different service provider. Follow the directions there.