With Skype, so far it has been possible to enjoy group calls (video or audio) within the limit of 25 participants. From now on, it is possible to call up to 50 people at the same time. Duplication of this limit has been announced for all groups with the latest version of Skype.
Changes are made at the same time to avoid certain interference. For group calls with more than 25 participants, there is no default ringtone. Group members will be notified to indicate that the call has started.
In that case, if the notice of the beginning of the call is insufficient, the user can use the ringtones melody individually for group members. For calls with less than 25 participants, this can be the ringtone ring for the entire group.
Remember that with relatively recent calls from the FaceTime group, a feature that has caused a big mistake to Apple, this is a limit for 32 people at the same time.