1. Off work, but available to provide a service if requested
   "I'm on call for my patients 4 days a week and every fourth weekend"

Encyclopedia: On call

• where's
• where've
• whereabouts
• whereafter
• whereas
• whereat
• whereby
• wherefore
• wherefrom
• wherein
• whereof
• whereon
• wheresoever
• whereto
• whereunto
• whereupon
• wherever
• wherewith
• wherewithal
• wherry
• whet
• whether
• whetstone
• whetter
• whew