As a business owner it is important to be there when a client needs you. Having the ability to communicate with clients no matter where you are can be a key to keeping clients happy. Sometimes quick answer is all that is needed and other times it means more work.
Understanding the demands and requirements of your job is key. Some jobs are 9-5 weekdays while more and more jobs are becoming flexible or variable hours. Most IT positions do involve some off hour work.
With technology changes more and more consulting work can be done remotely. This change means that quick changes can be done without having to travel to site and therefore getting a problem solved quicker.
In some cases a client doesn't even know you aren't in your normal location when you are assisting them. Understanding your responsibility of being there for your clients is what is important.
Being there for clients is important no matter where you really are.