There are very many different companies that offer VoIP. The number to call customer services will differ or each of them. For example to call Sipalto one would call 0207 1487525.
Yes, you can. You can call almost any country with VOIP.
Yes, VoIP service is as good as regular phone service - they have the same features and high call quality that can compete with traditional telephone services.
There are many options for VOIP phone service which are avaible anywhere you have High Speed internet service. The most popular one would be Vonage (www.vonage.com). Another option which could save you money if you call a single person who also uses VOIP, would be Skype (www.skype.com).
Call the toll-free telephone number 855-995-3652 to order small business VoIP service nationwide.
Whichvoip.com (http://www.whichvoip.com/voip/voip_faq.htm) has a lot of great FAQs to help you with general questions regarding VOIP. If you are using a specific carrier for your VOIP service, I would recommend contacting them directly for service issues.
The only real downside to VOIP home service is that the call quality may not be clear at all times. If your internet signal isn't good the phone call will not be good either.
If one wishes to purchase a PBX Virtual VoiP system, one would need to call a VoiP provider. The website, Virtual PBX is likely one's best option for this service.
That largely depends on the VoIP service you are using, but most of the time this is an available option.
The negative of using a VOIP provider is it relies on your internet connction. Also call quality can be suspect at times.
Switch2VoIP provides VoIP solutions for call centers in the US and nextiva offers VoIP and cloud-based call centers and is also located in the US. A third company providing VoIP call centers would be IntelePeer, Inc. and their services also include Canada.
You can contact your local Internet Service Provider to see if they offer Voip services. Another option would be to call Cisco directly at 866-428-9590 and ask them for help with finding a local reseller.