Frequently Asked Questions

Q. How much bandwidth do I need for VoIP?

A. A single VoIP call requires approximately 83Kbps of bandwidth unless compression is used (i.e. G.729 codec). However, bandwidth (i.e. the size of the pipe) alone is not the only parameter to consider when deploying VoIP. The quality of the connection (i.e. latency, jitter, etc) can also impact call quality. IsleCall engineers can help you ensure that you have enough bandwidth.

Q. Isn't all bandwidth the same? Is there something special I need for realible VoIP communications?

A. Bandwidth varies considerably in quality. While there has generally been incredible improvements in even the most inexpensive Internet connections, not all service provides a consistent level of service (i.e. consistent bandwidth, stable ping times, minimal jitter) that is suitable for VoIP. Typically these are referred to as "business class" Internet connections. While they cost a bit more than those used at home, they also come with quality guarantees and other features that make the cost differences worthwhile.

Q. I have a 6Mbps ADSL line so I can make lots of calls, right?

A. Maybe. The 6Mbps probably refers to the downstream bandwidth (the speed from the Internet to you) not the upstream speed (to the Internet). The upstream speed may be as slow as 384Kbps or 256KBps. In this case, you may only be able to have 1 call (or maybe 2 calls) depending on the quality of the connection. Also, without bandwidth management, checking email may cause quality issues.

Q. But if VoIP needs Internet access, is it reliable?

A. Actually yes - perhaps even more so than traditional "land lines". Most business class Internet connections are quite reliable today and rarely ever fail. Further, unlike traditional voice services, IsleCall permits the use of multiple Internet connections. This allows you to have a failover in case your primary Internet connection were to fail. Using failover, one can have a very highly available solution.

Q. What about 911 service? I have heard there are issues with that.

A. Back when VoIP got started, 911 service took some time to work out because it was different. However today we have E911 service and it works quite well, although some considerations need to be kept in mind. First, if you don't have power or Internet, obviously the phone service won't work and neither will 911. Also, because it works across the Internet, its important that your address is provisioned in our systems ahead of time so that the correct location is automatically sent to public safety when you dial 911. This requires that you tell us about each location, that you group each extension to its location, and that the Caller ID presented by your system when you dial 911 matches the location you are calling from. Obviously too, if you change locations, that information needs to get updated or we won't know. In short, it works well so long as its done properly.

Q. This all sounds too good to be true. Can it really cost less? What is the catch?

A. Yeah, we get that a lot actually. It may seem too good to be true. But its not smoke and mirrors - its really the simple concept of consolidation - the more we can leverage a single infrastructure to do different things, the more cost efficient it will be. Simlilarly, if we combine Internet access and phone service into a single connection its more efficient. Add to that the ability to move the calls across the Internet and we get even more efficient. Open-source software (Asterisk) has made this even more possible as its eliminated the dependency on expensive, proprietary phone systems.


Q. Ok. this is cool but I am lost. Can you help me figure this out?

A. Absolutely. We don't expect you to be a VoIP expert - that is our job. All you need to do is pick up the phone and call us at 800-867-ISLE, or This email address is being protected from spambots. You need JavaScript enabled to view it. and we will figure out what you need.