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Frequently asked questions about PHLO, Plivo’s drag-and-drop visual interface for building voice applications.

What is PHLO?

PHLO (Plivo High Level Objects) enables you to build voice applications without writing code using:
  • No XML or code required
  • Drag-and-drop components
  • Built-in testing
  • Instant deployment

How do I access PHLO?

Navigate to Voice > PHLO in the Plivo console.

What are the common use cases for PHLO?

Use CaseDescription
IVR SystemsBuild interactive menus with keypad input
Call RoutingRoute calls based on time, caller ID, or input
VoicemailRecord messages when unavailable
Call ForwardingForward calls to multiple destinations
Click-to-CallEnable website visitors to call you
Appointment RemindersAutomated outbound call campaigns

What trigger components are available?

ComponentDescription
Incoming CallStart workflow when call received
HTTP RequestStart workflow via API call

What action components are available?

ComponentDescription
Play AudioPlay pre-recorded audio file
SpeakText-to-speech message
Get InputCapture DTMF keypad input
RecordRecord caller’s voice
DialConnect to phone number or SIP
ConferenceJoin multi-party conference
HTTP RequestCall external webhook

What logic components are available?

ComponentDescription
BranchConditional routing based on input
SplitRoute based on multiple conditions

How do I design a PHLO workflow?

For step-by-step setup, see PHLO Getting Started.
  1. Drag components from the sidebar
  2. Connect components by drawing lines
  3. Configure each component’s settings
  4. Use branches for conditional logic

How do I test a PHLO?

  1. Click Test in the PHLO editor
  2. Simulate incoming calls
  3. Verify flow behavior
  4. Debug any issues

How do I deploy a PHLO?

  1. Click Save to deploy changes
  2. Assign phone number to PHLO
  3. PHLO is live immediately

How do I assign a phone number to a PHLO?

Method 1 (PHLO Editor):
  1. Open PHLO
  2. Click Assign Number
  3. Select available phone number
  4. Save
Method 2 (Phone Numbers):
  1. Go to Phone Numbers > Active
  2. Click on the number
  3. Select PHLO for Application Type
  4. Choose your PHLO from dropdown
  5. Update

What’s the difference between PHLO and XML Applications?

FeaturePHLOXML Application
SetupVisual, no codeRequires server + code
FlexibilityPre-built componentsUnlimited customization
HostingPlivo-hostedSelf-hosted
Best forSimple to moderate flowsComplex, dynamic applications

When should I choose PHLO?

  • Building standard IVR/routing flows
  • No development resources available
  • Quick deployment needed

When should I choose XML?

  • Complex business logic required
  • Integration with existing systems
  • Dynamic, data-driven call flows

What are design best practices for PHLO?

  • Keep workflows simple and focused
  • Use meaningful component names
  • Document complex logic with notes
  • Test all branches thoroughly

What are performance best practices for PHLO?

  • Minimize HTTP request latency
  • Use efficient audio files
  • Handle timeouts gracefully

Why aren’t calls reaching my PHLO?

Verify phone number assignment.

Why isn’t my branch working?

Check condition configuration.

Why isn’t audio playing?

Verify audio file URL accessibility.

Why is my HTTP request failing?

Check webhook URL and response.
For API triggering, see PHLO API Reference.