Teleconferencing services do not differ greatly, technically speaking. They amount to either operated-assisted conferencing or reservationless conferencing.  On the other hand, the feature set offered by either differs some what, as will service packages, fees, etc.. When choosing a teleconferencing service, consider the following:

1. Easy to book.
   Is a conference line easy to book? Can it be easily rescheduled, in case a key participant is unavailable?
   
   
2. Meeting overtime.
   If a meeting runs over the alloted time, will teleconferenced participants be dropped, or can you extend the call? Is there any extra connection fee for the call extension?
   
   
3. Ease of use.
   The more people that are expected to participate in a meeting, the more you'll want ease of use and ease of joining a call. When people outside the company participate, they may come in towards the end of a meeting. Can they join in, or is there a cut-off once the conference starts? (Some web-based conferencing software has this limitation.)
   
   
4. Call quality.
   Inexpensive is always good, but are the lines of good quality? Is there any crosstalk, dropouts, or ambient noise? You should have an opportunity to test a service's lines beforehand. What about clipping? Does the conferencing equipment cause voice clipping if two or more people speak simultaneously? (This is a concern if the equipment is supplied by the service as part of your conference line subscription. If you are purchasing your own equipment, you will have to test this after line subscription.)
   
   
5. Recording option.
   Is there an option for recording and storage of conference calls, and is it secure? With numerous new business regulations imposed by the U.S. and other governments, such as the Sarbanes-Oxley Act, compliance may mean that public and sometimes even non-public companies need to record all phone conversations that go beyond the borders of the office. This is especially important if, say, shareholders are part of a conference call. Audio recordings may also need to be stored for an extended period of time, in a safe, secure place. Is there a provision for doing this with minimum effort?
   
   
6. Cost.
   How is the conferencing service fee structured? Do you pay for the line, or also for each connection to a call? Is there a volume discount for long-term recurring meetings? Do they supply conferencing equipment such as speakerphones as part of the subscription package, or is that a separate purchase?
   
   
7. Advanced features.
   What advanced teleconference service features are offered? Will they be anything you would actually use now or in the near future? Do you have to pay for them even if you don't use them, or are there more basic service packages?

Obviously, not everyone will care about  all of the above criteria or features. However, being aware of your options may prove useful if your teleconference needs change in the future.

Before choosing a service, it's best to make three feature lists:

1. Features you need now.
2. Features you will need in the near future.
3. Features that are nice to haves.

Making this distinction will make it easier for you to choose the most appopriate service.