A telephone call is elevated to a virtual meeting while maintaining the telephone call as an audio channel of the virtual meeting for an audio-only caller. During a telephone call, one of the participants of the telephone call requests to switch the telephone call to a virtual meeting. To enable an audio-only caller participating in the telephone call to switch to the virtual meeting, a message is transmitted to the phone device of the audio-only caller. Responsive to an interaction with the message at the phone device, the phone device is connected to the virtual meeting in which the telephone call is maintained as the audio channel at least for the audio-only caller. The specific form and content of the message is based on whether a client application associated with a web service used to implement the virtual meeting is installed on the phone device.