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Frequently asked questions about Voice API concepts, CPS limits, geo permissions, caller ID, STIR/SHAKEN, and call management.

What are CPS limits and how do they work?

CPS limits control how many calls your account can initiate or receive per second.
TypeDefaultDescription
Outbound CPS2API-initiated calls
Inbound CPS10Incoming calls + outbound from SIP/browser clients

What happens when calls exceed outbound CPS?

Calls are queued rather than dropped and dispatched when the rate decreases. Example: With a 10 CPS limit, initiating 12 calls results in the first 10 executing immediately while the remaining 2 queue for the next interval.

How are inbound calls handled when CPS limits are exceeded?

Incoming calls surpassing the inbound CPS threshold are rejected with SIP code 486.

What’s the difference between CPS and concurrent calls?

MetricDefinition
CPSRate of new call initiation per second
ConcurrentTotal active calls at any moment (no fixed limit)

How can I increase my CPS limit?

Contact Plivo Support to request a CPS increase for your account.

What are geo permissions and which regions are enabled by default?

Geo permissions control international calling destinations. Only the US or India is enabled by default (based on your account currency). Enabling other countries requires an Enterprise account.

How do I configure geo permissions?

  1. Navigate to Voice > Geo Permissions in the console
  2. Enable countries where you need to make calls
  3. Keep unused countries disabled for security

What error occurs when calling to restricted countries?

Calls fail with the hangup cause destination_country_barred when the destination country isn’t enabled in geo permissions.

Can I manage geo permissions programmatically?

Yes, use the Voice Geo Permissions API to manage permissions programmatically.

What is verified caller ID and why is it important?

Verified caller ID authenticates numbers before using as outbound caller ID. Verification ensures compliance with carrier requirements and prevents calls from failing due to unverified caller ID. Verification can be done through the Plivo Console, APIs, or SDKs.

What is the Do Not Originate (DNO) list?

Calls using numbers on the US Telecom DNO list fail with the dno_caller_id hangup cause. These numbers, reserved for government agencies and financial institutions, are inbound-only.

What is STIR/SHAKEN and why does it matter?

STIR/SHAKEN is the FCC-mandated call authentication framework to combat spoofing and robocalls.

What are the three STIR/SHAKEN attestation levels?

LevelMeaning
A (Full)Carrier verified caller identity and authorization
B (Partial)Carrier verified the customer but not specific number authorization
C (Gateway)Call originated from a gateway with no customer verification

What KYC information does Plivo need for STIR/SHAKEN?

  • Company name and website
  • Business registration number/documents
  • Nature of business
  • Use case for Plivo
Note: STIR/SHAKEN applies only to US businesses.

How do I set up voice alerts?

  1. Navigate to Voice > Settings > Alerts in the console
  2. Configure thresholds for:
    • Invalid XML responses
    • Call failure rates
    • Unusual traffic patterns

How do I cancel queued calls?

For making outbound calls, see Make Outbound Calls Guide. Use the Hangup API with the request_uuid from the queued call to cancel it.

What is PreAnswer functionality?

PreAnswer allows playing audio before a call is answered (early media). Supported elements: <Speak>, <Play>, <Wait> Limitations:
  • Variable carrier support
  • No WebRTC SDK support
  • Destination-dependent accuracy

Where can I find hangup cause information?

Hangup information is available in:
  • Call Detail Records (CDR) via API or Console
  • Callback payloads to hangup_url
  • Dial XML callbackUrl for DialHangup events

What are common hangup causes and their solutions?

CauseSolution
destination_country_barredEnable the country in settings
unknown_caller_idUse a Plivo number
dno_caller_idUse a different caller ID
violates_media_anchoringKeep media within India
See Hangup Causes Reference for complete list.

How do I export recent CDRs?

  1. Navigate to Voice > Logs > Calls
  2. Apply filters
  3. Select CDRs
  4. Click Export > Export Filtered Results
Large exports are emailed to your registered address.

How do I access historical CDRs?

  1. Go to Voice > Logs > Calls
  2. Click Export > Export Historical Data
  3. Select account/subaccount and date range

What information is included in CDRs?

CDR fields include: Call UUID, From/To numbers, direction, duration, billed amount, hangup cause, and more. Note: Numbers in CDRs older than 90 days are redacted.

How does Plivo cache audio files?

Plivo caches audio files used in <Play> XML and Play API. Each media server maintains its own cache, and first requests always result in a cache miss.

How can I control caching behavior?

HeaderBehavior
Cache-Control: no-storeNever cache
Cache-Control: no-cacheAlways check for updates
Cache-Control: max-age=<seconds>Cache for specified duration
ETagEnable conditional requests

How do I create an application?

  1. Navigate to Voice > XML > Add New Application
  2. Enter the application name
  3. Configure the answer URL and other settings
  4. Click Create Application

How do I assign a number to an application?

  1. Go to Phone Numbers > Active
  2. Click the number
  3. Select XML Application
  4. Choose your application
  5. Save

What causes common call quality issues and how do I fix them?

IssueCauseSolution
EchoAcoustic feedback/network delayCheck endpoint audio settings
Choppy audioCongestion/packet lossCheck connection, reduce bandwidth
One-way audioFirewall blockingWhitelist Plivo IP ranges
LatencyDistance/routingUse nearest Plivo PoP

How do I monitor application health?

Check for 4xx/5xx status codes indicating invalid XML responses, API request failures, or configuration errors. Set up Voice Alerts to proactively detect issues.

What caller ID restrictions exist in Australia?

Per ACMA regulations, blocked CLI prefixes include +6113, +611300, +611800, and +611900. CLI modifications or spoofing are flagged by spam detection.

What restrictions apply to calls in China?

Prohibited:
  • Gambling, financial services, cryptocurrency
  • Marketing/spam calls
  • Fraudulent calls
  • Politically sensitive content
Requirements:
  • Average call duration over 3 minutes
  • Avoid high unanswered rates
  • No toll-free caller IDs
Contact Plivo Support to enable China calling.

How do I access pricing information?

Access pricing by country through:
  • Console: Voice > Pricing
  • API: Pricing API
  • CSV export from console