The answer depends on the audio conferencing service you are using.
Reservationless (On Demand) Audio Conferencing
You can have a maximum of 125 connections on any given reservationless audio conferencing call. Keep in mind some of these connections on your call might be a phone from a boardroom and there may be more than one person in that boardroom. Therefore, to maximize the number of PEOPLE you can have on a reservationless audio conferencing call, try to encourage as many people into a boardroom as you deem comfortable and try to have as many boardroom connections as possible (rather than having everyone calling from their person or workstation phone). Just a friendly suggestion to maximize the participation turnout on these calls.
Event (Operator-Assisted) Conferencing
Event calls can accommodate for hundreds of participants and in some cases, thousands. There isn't any set in stone cap on the maximum number of participants. Since the size of the Event call truly depends on the nature of your meeting, simply reach out to Pragmatic so that we can understand what you are trying to achieve for your meeting and we will ensure the most appropriate service is being used.