How Can We Help?

Unit – Setting up Three Way Calls

This unit will cover how to set up three-way conference calls with Fastcall. This is necessary to use the Fastcall features listen-in and warm call transfers but does have some trade-offs.


Fastcall uses three-way conference calls to power two features: listen-in and warm call transfers. A conference call is handled differently from a normal call by Twilio and costs more than normal 2-leg calls.

Fastcall Listen In (discussed in the next unit) requires the call to start as a conference call so that the manager or trainer can join the call at any time during the call. All calls (to given Users) will be started as three-way conference calls. When an inbound or outbound call is made, a conference is started and two participants are added. Then, when the listening user joins, a third conference participant is added. Warm transfers also use 3 legs, but these conference calls are created on-demand.

Cost implications

Turning on this feature will increase the cost of calls. As well as charging for each call connected to the conference, Twilio will charge a per-minute fee for the conference itself. This means that the per-minute call costs will be higher when using this feature.

Complexity implications

Whilst the functionality is stable and proven, conference calls are inherently more complicated than normal calls – there are more participants, and Twilio is doing more work behind the scenes. This means there’s more to break.

Consider who needs this

Consider alternatives to listen-in and warm call transfer, such as reviewing call recordings and cold transfers. You can also limit which users or groups get access to this functionality.


Three-way conference calling is enabled and controlled in Fastcall Settings > Admin Settings > Call Handling > 3 Way Call Settings.

3 way call settings

Enabled for

You can select a specific User or Group for three-way conference calls. As mentioned, conference calls behave differently from normal calls, so you may wish to limit which Users get this functionality.

Pass inbound Caller ID

This setting makes Fastcall pass the original inbound caller ID to the new person. So, for example, if Contact Alice makes an inbound call to User Bob, and then User Bob makes a warm transfer to User Charles, Charles will see that Alice is calling him. If this feature is left off, Charles will see that Bob is calling him. Turning this feature requires additional permissions to be granted in Twilio. Please contact Fastcall to discuss this.

Audio settings for 3 way call

It’s recommended that you set some audio, otherwise, call participants may think they have been disconnected while Twilio makes the other connections involved in the conference call. You do not want silence in this setting.

Last updated: Fastcall v8.0.0, 2023-03-23

Ready to start the Free Trial?

Provide your information and install the package in your Salesforce Org.

Please enter your email to join the Fastcall Appexchange
Enter your work email and we will contact you to schedule a demo