i need some info on usar for collage work

[jackus]

hi i am interested in joining the fire service and hopefully join usar for a specialist job so i was just wondering what i would have to do to join up and what things i would be facing doing this job?
also i would like to know strictly for my collage does the police and ambulance service have some sort of usar team to help the fire service or is it just for fire service?
also is usar only volentry as i cant find any decent info on usar on the internet

so if any of you can help me it would benifit me and others in my public services group

thanks
jack