Dial in or dial out
Participating a teleconference can be done via Dial-in or dial-out. In the case of dial-in each participant calls an access number of the teleconference provider. An interactive voice response system asks and validates the access codes entered by the chairperson and participants. In the case of dial out participants are called by the teleconference provider. This is convenient for them but more expensive for the organizer.
In the case of dial in two approaches can be distinguished dependent of who pays for the conferencing costs.
The organizer pays for the conferencing costs
This is the most common way of teleconferencing. Participants call to a regional dial-in number for their participation. The better conferencing providers have local access numbers in different countries.
Some provides offer toll free numbers for totally free participation. This solution is more expensive for the organizer who is charged for the telephony costs.
The participant pays for the conferencing costs
Participants call to a premium service number*. They pay for their own participation through the invoice of their own phone.
* Attention: some providers use "hidden" service numbers; phone numbers that are generally not recognized as premium rate numbers (like 084- of 087-numbers in The Netherlands). To prevent extremely high phone bills you'd better avoid these providers.
With dial out participants are called for their participation. This is very convenient and totally free of charge for the participants. A dial out teleconference can be set up by operators of the conferencing provider that call each participant individually and place her or him in the teleconference. Some conferencing providers offer the possibility to organizers to start a dial out a conference call without the help of an operator. Dial-out is more expensive than dial in because all telephony costs are charged to the organizer. If dial out is executed by personnel of the teleconference provider additional setup costs will be charged.