The document discusses the design and implementation of multi-party call flows using Twilio, outlining key features such as hold, transfers, and supervisor monitoring. It details technical aspects, including call control building blocks and event handling, with examples of how to set up conferences for inbound and outbound calls. The authors encourage developers to utilize these features for various applications, including support and sales contact centers.

1. a
DESIGNING MULTI-PARTY CALL FLOWS
ANDREW JORDAN | AMEYA

2. WE’RE GOING TO ANSWER THE FOLLOWING
What do we mean by multi party?
What features does this call flow unlock?
What use cases lend themselves to a multi party call flow?
How do I implement these features in my application?
ANDREW JORDAN | AMEYA

3. MULTI PARTY, WHAT DOES
THAT MEAN?

4. TWO PARTY VS N PARTY
• Simple to implement
• Can be stateless
• <Number><Client><SIP>
ANDREW JORDAN | AMEYA
• Robust call control
• Stateful tracking of participants
• <Conference>
A B A B
C
D

5. ANDREW JORDAN | AMEYA
WHAT FEATURES DOES MULTI PARTY UNLOCK
• Hold
• Warm and Cold Transfers
• Supervisor Monitoring / Barge

6. ANDREW JORDAN | AMEYA
WHAT DO YOU BUILD WITH THESE FEATURES?
• Inbound Support Contact Centers
• Outbound Sales Contact Centers
• Lead Management Platforms
• Incident Management Platforms

7. LETS GET TECHNICAL

8. A B

9. ANDREW JORDAN | AMEYA
A customer requesting
support calls into a Twilio
phone number, and the
agent and customer are
put into a conference.
INBOUND CALL
TO CONFERENCE
1. Inbound call from the customer
2. Customer’s Call receives the following TwiML
<Response>
<Dial>
<Conference Waiturl=“foo.bar/wait”>SupportID1234</Conference>
</Dial>
</Response>
3. Outbound REST API call to Agent
4. Agent’s call receives the following TwiML
<Response>
<Dial>
<Conference>SupportID1234</Conference>
</Dial>
</Response>

10. ANDREW JORDAN | AMEYA
1. Outbound REST API call to the Sales Agent
2. Agent’s Call receives the following TwiML
<Response>
<Dial>
<Conference>AgentID1234</Conference>
</Dial>
</Response>
3. Outbound REST API call to prospect
4. prospect’s call receives the following TwiML
<Response>
<Dial>
<Conference>AgentID1234</Conference>
</Dial>
</Response>
A sales agent calls out to
a prospect and both the
agent and prospect are
put into a conference.
OUTBOUND CALL
TO CONFERENCE

14. CALL CONTROL BUILDING
BLOCKS
MUTE / TRANSFER / HOLD /
EVENTS

15. ANDREW JORDAN | AMEYA
Mutes or unmutes a
participant in a
conference
MUTE
$ curl -XPOST /Conference/CFbbe46ff1274e283f7e3ac1df0072ab39/
Participants/CA386025c9bf5d6052a1d1ea42b4d16662
-d "Mute=true"
-u 'AC123:{AuthToken}'

16. ANDREW JORDAN | AMEYA
$ curl -XPOST /Accounts/AC25e16e9a716a4a1786a7c83f58e30482/
Calls/CA386025c9bf5d6052a1d1ea42b4d16662.json
-d "Url=https://myapp.com/transfer"
-d "Method=POST"
-u 'AC123:{AuthToken}'
Redirects a call that is
executing a TwiML
document to execute a
new TwiML document
TRANSFER

17. ANDREW JORDAN | AMEYA
$ curl -XPOST /Conference/CFbbe46ff1274e283f7e3ac1df0072ab39/
Participants/CA386025c9bf5d6052a1d1ea42b4d16662
-d "Hold=True"
-d "HoldUrl=https://myapp.com/hold"
-u 'AC123:{AuthToken}'
Redirects the media
stream of one participant
away from the
conference mix to a
TwiML document at the
HoldUrl
HOLD

18. ANDREW JORDAN | AMEYA
Webhooks that are fired
when conferences and
participants change state.
Supported state changes
are “start end join leave
mute hold”
EVENTS <Response>
<Dial>
<Conference
statusCallback="https://myapp.com/events"
statusCallbackEvent="start end join leave mute hold”>
room1
</Conference>
</Dial>
</Response>
FriendlyName EventedConference
ConferenceSid CFbbe46ff1274e283f7e3ac1df0072ab39
EndConferenceOnExit false
CallSid CA912194cbf5baa015e0c9755feee7a92c
StatusCallbackEvent participant-join
StartConferenceOnEnter true
AccountSid AC25e16e9a716a4a1786a7c83f58e30482&
Muted false
Hold false

19. I’D LIKE TO SPEAK TO THE
MANAGER

20. WARM TRANSFER DEMO

21. ANDREW JORDAN | AMEYA
1. Customer A Joins
2. Agent B Joins
3. A and B talk and need
to bring in C
4. A is put on hold
5. Agent C joins
6. Agent B and C discuss
7. Customer A is removed
from hold
8. All parties are
introduced
9. B leaves
A B
C
Event: participant-join Store: ConferenceSidEvent: participant-join Store: ConferenceSidParticipant Held REST API: Hold=trueEvent: participant-hold Store: Participant StateEvent: participant-join Store: ConferenceSidEvent: participant-leave Store: Participant StateParticipant Held REST API: Hold=falseParticipant Unheld Store: Participant State

22. MONITOR / BARGE

23. ANDREW JORDAN | AMEYA
1. Customer A Joins
2. Agent B Joins
3. Supervisor C joins on
mute
4. C can hear A and B but
A and B cannot hear C
5. C is un muted to
handle escalation A B
C

24. ANDREW JORDAN | AMEYA
1. Customer A Joins
2. Agent B Joins
3. Supervisor C joins on
mute
4. C can hear A and B but
A and B cannot hear C
5. C is un-muted to
handle escalation
A B
C
Event: participant-join Store: ConferenceSidEvent: participant-join Store: ConferenceSidParticipant Unmuted REST API: Mute=false

25. RECAP
Using Conference allows you to build robust multi party call flows
We see thousands of Twilio customers utilizing this architecture
We’re released features like Events and Hold to streamline these flows
We’re continuing to develop features to enable multi party call flows
ANDREW JORDAN | AMEYA

26. WE CAN’T WAIT TO SEE
WHAT YOU BUILD

27. YOUR NAME | TWITTER
ANDREW + AMEYA @TWILIO.COM