Audio Overview

Webex Teleconference Audio includes 'Call me' and 'Call in' in-session audio options. There are three types of Teleconference Audio – Public Switched Telephone Network (PSTN), Webex Cloud Connected Audio (Webex CCA), and Webex Edge Audio. Having all three different types in mind, if you face an audio issue with 'Call in' or 'Call me,' please first reach out to your local support.

Public Switched Telephone Network (PSTN) 

Cisco Webex Audio provides a broad coverage footprint with Toll dial-in, toll-free dial-in, and call-me capabilities for local and global connections as a cloud-based PSTN audio option. It operates on various devices, including cell phones, IP phones, and softphones. It supports the ability to enable telephony attendees and attendees and devices that use Voice over IP (VoIP) to all collaborate in the same session.

Cisco Webex Cloud Connected Audio (CCA)

Cisco Webex Cloud Connected Audio is an audio-conferencing service naturally integrated into Webex meetings that provides internal and external users with the best and most consistent experience to improve meeting effectiveness. It can be delivered from a service provider as-a-service or through direct enterprise architecture.

• What's New in the Webex Cloud Connected Audio Portal
• Terminate Live Meetings from the Cisco Webex Cloud Connected Audio Portal
• Manage Telephony Domains
• View Customer Reports in the Webex Cloud Connected Audio Portal
• Manage Callback Groups
• Manage Users in The WebEx Cloud Connected Audio Portal

Webex Edge Audio

With Webex Edge Audio you can decouple the public switched telephone network (PSTN) from Webex by intelligently changing the call routing to a simple-to-deploy on-network path.
Webex Edge Audio creates a VoIP path for Cisco Unified Communications Manager (CM) registered devices, whether users are dialing in or requesting a callback.  For non-Unified CM registered phones or mobile devices, the company's own PSTN services can be used.

See the following for more information: Webex Edge Connect