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DialNexa routes India calls through Plivo’s India carrier infrastructure. This reduces PSTN latency compared to routing through global (typically US-based) carrier interconnects. For transcription, DialNexa uses the Soniox transcriber with Hindi language hints configured by default for Indian numbers. For text-to-speech, Sarvam AI is the recommended option for Indian language calls, with en-IN as the default locale.

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What India Routing Actually Does

When you use an Indian phone number provisioned through DialNexa (via Plivo):
  • PSTN routing: Calls route through Plivo’s India carrier infrastructure, reducing the network path between the Indian PSTN and DialNexa’s call processing
  • Transcription: The Soniox transcriber is configured with Hindi language hints for Indian numbers by default, which improves transcription accuracy for Hindi-accented English and Hindi-language calls
  • TTS: Sarvam AI is available as a TTS option and defaults to en-IN - it is the recommended provider for Indian language calls
There is no separately branded “India region” data center with distinct data residency guarantees. See Data Residency for accurate information about where call data is stored.

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Why Plivo IN Routing Matters

Calls that originate in India but route through international carrier interconnects add latency at the PSTN level before DialNexa even begins processing. Using Plivo’s India infrastructure means:
  • The call reaches DialNexa’s processing pipeline via a shorter carrier path
  • Outbound calls to Indian numbers originate from Plivo’s India carrier points, which Indian networks treat as domestic traffic
  • Audio quality is generally better because fewer cross-border carrier hops are involved

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Transcription: Soniox with Hindi Language Hints

For Indian numbers, the Soniox transcriber is configured with Hindi language hints by default. This tells Soniox to expect Hindi or Hindi-accented English speech, which improves transcription accuracy for:
  • Callers speaking Hindi
  • Callers speaking English with a Hindi accent
  • Callers code-switching between Hindi and English
If your use case is exclusively English (e.g., enterprise B2B calls), you can remove the Hindi hints and use Deepgram Nova 3 for lower-latency English transcription.

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TTS: Sarvam AI for Indian Language Calls

Sarvam AI is a TTS provider built for Indian languages. It supports Hindi, Tamil, Telugu, Kannada, Malayalam, Bengali, Marathi, Gujarati, and Indian English. When using Sarvam AI in DialNexa:
  • The default locale is en-IN (Indian English)
  • Switch the locale to your target language for agents that speak Hindi or other Indian languages
  • Sarvam AI is the recommended TTS for any agent that needs to produce natural-sounding Indian language audio
For English-only agents serving Indian callers, Cartesia is also a suitable TTS option with lower latency.
ComponentRecommended optionWhy
Phone numberIndian number via PlivoRoutes through Plivo India infrastructure
TranscriberSoniox (Hindi hints enabled)Better accuracy for Hindi and Indian English
TTSSarvam AI (en-IN or target language)Natural-sounding Indian language voices
LLMGPT-4o Mini or Groq (Llama 4)Lower inference latency

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Setting Up India Routing

1

Purchase or connect an Indian phone number

Go to Phone Numbers in the dashboard and purchase an Indian number. This provisions the number via Plivo’s India catalogue. See Regulated Phone Numbers.
2

Assign the number to your agent

In the agent configuration, assign the Indian number as the outbound caller ID or inbound number.
3

Configure the transcriber

In the agent’s voice settings, select Soniox as the transcriber. Hindi language hints are applied by default for Indian numbers.
4

Configure TTS

For Indian language calls, select Sarvam AI as the TTS provider. Choose the appropriate locale (en-IN for Indian English, or the target language for multilingual agents).
5

Test with a real call

Make a test call from an Indian mobile number. Review per-turn latency and transcription quality in the call detail page.
Calls from Indian callers to DialNexa agents travel a path that includes multiple network hops: from the caller’s phone, through the Indian PSTN carrier, to DialNexa’s call processing servers, and back. The geographic location of those processing servers has a direct impact on call latency and audio quality. Indian server routing ensures that call processing - transcription, LLM inference coordination, TTS synthesis - happens in servers located within India, minimizing the round-trip time for Indian callers.

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Why Server Location Matters for Call Quality

Voice calls are real-time - there is no buffering to hide latency. Every millisecond of network delay adds up to perceived lag. The primary contributing factors:
  • Geographic round-trip: A call processed in a US data center adds 150-200ms of one-way network latency for Indian callers, compared to 10-30ms for India-based servers.
  • PSTN routing: Calls that originate in India but are routed to international servers pass through cross-border carrier interconnects, which add latency and occasionally introduce packet loss.
  • Transcription processing: Audio must travel to the transcription service and the transcript must travel back. Processing this in India eliminates the cross-border trip.
The cumulative effect of routing through geographically distant servers can add 300-400ms to total turn latency - a significant portion of the target 1-1.5 second total latency budget.

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What Indian Server Routing Affects

When India routing is enabled for a workspace, the following processing happens in DialNexa’s India infrastructure:
Processing stageWith India routingWithout India routing
PSTN call terminationIndian carrier infrastructureGlobal (typically US)
Voice activity detectionIndia serversGlobal servers
Transcription coordinationIndia serversGlobal servers
LLM request routingIndia servers (to LLM API)Global servers (to LLM API)
TTS coordinationIndia servers (to TTS API)Global servers (to TTS API)
Call data storageIndia data centerGlobal data center
India server routing reduces the network path from caller to DialNexa. The underlying LLM API (OpenAI, Anthropic) and TTS API (Cartesia, ElevenLabs) are still third-party services that DialNexa calls on your behalf. Those API calls originate from DialNexa’s India servers, not from global servers - this reduces latency compared to global routing, but the LLM and TTS services themselves are not necessarily India-based.

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Expected Latency Improvement

Benchmark comparison for a typical Indian caller (Mumbai) to a DialNexa agent:
ConfigurationTotal turn latency (approximate)
Global routing, GPT-4o, ElevenLabs2.5 - 4.0 seconds
India routing, GPT-4o, ElevenLabs1.8 - 2.8 seconds
India routing, GPT-4o Mini, Cartesia1.0 - 1.6 seconds
India routing, GPT-4o Mini, Cartesia + Audio Cache0.6 - 1.2 seconds (for cached phrases)
For the best call experience for Indian callers, combine India routing with the fast model and TTS selections. See Latency for the full optimization guide.

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PSTN Routing via Indian Carriers

DialNexa’s India-based telephony infrastructure connects to the Indian PSTN via direct interconnects with Indian carriers. This means:
  • Inbound calls to Indian numbers purchased through DialNexa route to DialNexa’s India data center directly, without crossing international carrier interconnects
  • Outbound calls to Indian mobile and landline numbers originate from DialNexa’s India carrier infrastructure, resulting in shorter PSTN path and better audio quality
  • Local number identification: outbound calls show an Indian number caller ID (matching your purchased or BYOT number), which Indian carriers treat as domestic traffic
If you bring your own number via a BYO SIP trunk, the PSTN routing depends on your carrier’s Indian infrastructure.

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Enabling India Routing

India routing is enabled at the workspace level by selecting the India region when creating the workspace.
1

Create or use an India-region workspace

India server routing is automatically active for all workspaces created with the India data region. If your workspace is on a global region, you need to create a new workspace with the India region selected. See Data Residency for the workspace creation process.
2

Purchase or configure an Indian phone number

For India routing to apply to PSTN calls, the phone number associated with the agent must be an Indian number routed through DialNexa’s India carrier infrastructure. Purchase a number in the Phone Numbers section of the dashboard.
3

Select India-compatible components

To maximize the latency benefit, also select:
  • LLM: GPT-4o Mini or Groq Llama 4 (fastest inference)
  • Transcriber: Deepgram Nova 3 (lowest STT latency)
  • TTS: Cartesia (lowest first-audio latency)
4

Test with a real call

Make a test call from an Indian mobile network. Review the per-turn latency breakdown in the call detail page to confirm the improvement.

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Verifying India Routing Is Active

On any call detail page, the Infrastructure section shows which server region processed the call. When India routing is active, you’ll see Region: India in this section. If it shows a global region, verify that the workspace was created with the India region selected.

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Web Calls and India Routing

Web calls (browser-based calls using the React SDK) also benefit from India routing when the workspace is configured with the India region. The WebRTC connection is established with DialNexa’s India-based media servers, reducing latency for users accessing your web application from India. For Indian users of your web application, the latency benefit of India routing on web calls is similar to PSTN calls: approximately 300-400ms reduction compared to global servers.