Phone numbers

Provision phone numbers for voice, SMS, and WhatsApp agents — buy from a provider or bring your own existing number.

A phone number is your agent's identity on the public phone network. Voice agents need one to receive or place calls, SMS agents need one to text, and WhatsApp agents need a WhatsApp-Business-enabled number.

Two ways to get a number

Option 1 — Buy through your provider

Twilio and Plivo both let you buy numbers in minutes. Sign in to their console, pick a country and area code, and the number is yours.

Once you have a number on the provider side, Dashboard → Numbers in Nerva to add it. You'll paste:

Your provider account credentials
The phone number

Nerva configures the webhooks on the provider so calls and messages route to us.

Option 2 — Bring your own existing number

If you already have a Twilio or Plivo number, follow the same import steps as Option 1. We don't take ownership of the number — your provider account keeps it; we just configure routing.

If you have a number with a different carrier (e.g., your office landline), you can port it to Twilio or Plivo first, then import. Porting takes 2–4 weeks depending on the carrier — start early.

Number capabilities

Different numbers support different capabilities. Check on your provider when buying:

Capability	Required for
Voice	Voice agents (inbound and outbound calls)
SMS	SMS agents
MMS	SMS agents that send media (images, etc.)
Fax	Not used by Nerva

A single number can have any combination of capabilities. A US local number with Voice + SMS is the most common starting point.

WhatsApp Business is not a number capability in the carrier sense — it's a separate Meta-side registration on top of an existing number. See WhatsApp agents for the migration flow.

US 10DLC registration (for SMS)

Sending SMS to US numbers via long codes (regular 10-digit numbers) requires A2P 10DLC registration:

Register your brand (your business identity) with The Campaign Registry (TCR), usually via your provider's console.
Register a campaign describing what you'll send (use case, message volumes, sample content).
Wait for approval — usually 1–3 business days.

Without 10DLC registration, your US SMS sends will be filtered by carriers (silently dropped) within days of starting. Plan for this if SMS is part of your launch.

Toll-free SMS numbers have a different (simpler) verification flow — also done through your provider.

Number countries

Twilio and Plivo both offer numbers in 100+ countries. Pricing varies significantly:

US / Canada — cheap (often under $1/month per number) and instant.
UK / Germany / France — moderate. Sometimes requires address verification.
India — requires DLT registration and significantly more paperwork.
Australia / Singapore — moderate, may require business verification.

When buying, your provider will show you any country-specific requirements before purchase.

Assigning a number to an agent

In Dashboard → Numbers, each number has an Assigned to dropdown. Pick the agent that should handle calls/SMS to that number.

One number = one agent at a time. If you change the assignment, future calls/messages route to the new agent immediately.

Multiple numbers per agent

You can assign multiple numbers to the same agent if you want one agent answering across several inbound numbers (e.g., one number per campaign, one main support number). Just assign each number to the same agent.

Outbound caller ID

For outbound calls (single dial or campaigns), the outbound caller ID is the number you've assigned to the agent. If the agent has multiple numbers, the campaign config picks one as the caller ID.

Recording

Voice numbers automatically record both legs of every call. Recordings are uploaded to your configured S3 bucket and surfaced on each call's detail page. Toggle off per-agent in the agent editor if you don't want recording.

Some regions require two-party consent for recording (e.g., several US states, much of the EU). Configure your agent's greeting to disclose that the call is recorded if you're operating there.

Cost

Number costs come from your provider (Twilio / Plivo), not Nerva. Typical monthly costs:

US local voice + SMS: ~$1.15/month + per-minute usage
Toll-free: ~$2–5/month + per-minute usage
International: varies widely

Nerva's per-minute pricing covers our platform + STT/LLM/TTS providers — see Billing & plans. The provider charges are separate on your provider invoice.

Number limits

Each plan has a maxPhoneNumbers cap. Adding numbers beyond the cap requires upgrading. See Billing & plans.

Troubleshooting

Symptom	Likely cause	Fix
Number imported but calls don't reach the agent	Webhook URL on provider points to old/wrong endpoint	Re-import; Nerva sets the webhook URL on import
US SMS sends never deliver	10DLC not registered, or campaign rejected	Check Twilio/Plivo console, complete brand+campaign registration
Outbound calls fail with "spam-likely" caller ID	Your number is flagged by carrier analytics	Lower call volume, vary numbers, register with caller-ID services like FreeCallerRegistry
Number stops working after a few days	Provider trial limits hit, or low balance	Add billing on the provider side
WhatsApp says "number cannot register"	Number is already registered to a Meta account, or already a WhatsApp user	Reset on the provider side or pick a fresh number