Some online companies are able to have 24 hour phone service...is this expected, or rather, worth going the extra mile for? It seems like it would be quite costly to maintain, but our company might be doing some global business so timezones are an issue. How do other people deal with this?

most of those overseas phone services are based overseas such as India,Philippines....etc

Yeah, I think 24/7 phone service is going to be near impossible for a small business like you. I wouldn't worry too much about it, people expect it from companies like guitar center or amazon but not a mom and pop online store, if you will. However, I think being somehow REACHABLE 24/7 is good. Leaving an email address, for example, or getting a good voicemail service or another advanced 1-800. Some of them, like gotvmail, also do local numbers, if you'd rather not pay for a 1-800. Anyway the point is that when customers call they should hear something professional on the other end, even if you can't pick up. I've had clients go under as a result of poor customer service, in fact.

I think it really depends what business you are in - and what your visitors expect of you.

Probably 95% of online businesses manage perfectly well on email contact for all but local people.

But if your competitors offer it, then you can't ignore it!

Have you considered live chat? There are a number of inexpensive live chat applications available. Then, so long as you are near a computer in your waking hours, you can provide a live chat service for the vast majority of each day e.g. 16+ hours per day.