I'm not personally familiar with Starhub, but VOIP service in general works the same regardless of the carrier. They all require a high-speed internet connection in addition to a VOIP modem (modem supplied by VOIP provider). You can then connect the VOIP modem into your regular phone wiring, which allows you to use connect regular phones to your existing phone jacks.

Advantages:

1. It's usually much cheaper than regular landline service (about half the price)
2. Since it's Internet-based, your number has no physical boundary, so you could take your VOIP modem anywhere in the world and continue to use your regular telephone number.
3. You can usually get a number from another city if you wish, so that if you have a lot of friends and family in a different area they can call you as a local call.

Disadvantages:

1. The quality can often be quite poor since it relies on the public Inernet to carry the signal, can frequently lose connection alltogether.
2. If your power goes out - no phone
3. If you have to call 911, you won't get a regular 911 operator, you'll get a Starhub operator who then requests all the information of where in the world you are (since you could be anywhere), this means if you can't talk, then 911 won't help.

Hope this helps a bit.