# Tata Smartflo

Source: https://docs.usetone.ai/sip-trunking/tata-smartflo

> Route a Tata Communications enterprise SIP trunk to Tone — what to put on the provisioning form, and what usually breaks first.

*Tata's Smartflo is a managed enterprise trunk: provisioning is done by Tata, not by you, so most
of this page is about asking for the right thing the first time.*

**Not yet validated end to end by Tone against a live Smartflo trunk.** Every Tone-side field below
is exact. The Tata-side steps are a specification to hand your account manager rather than a
click-path, because Smartflo trunks are configured by Tata's provisioning team and the portal
differs by contract. If you run this, tell support@usetone.ai what you hit.

## Before you start

- A Smartflo contract with DIDs allocated, and a named Tata account manager or provisioning
  contact.
- A Tone organization with KYC verified and **SIP trunking** enabled by Tone support.
- Your trunk's page in the Tone dashboard open — it carries the signalling IPs Tata must allow,
  which are specific to your deployment.

## The provisioning request

Managed Indian trunks are delivered against a form. Send all of this at once:

| They need | Value |
|---|---|
| Our SIP endpoint (for inbound delivery) | `sip.usetone.ai` |
| Transport | TLS on `5061` — or TCP/UDP on `5060` if TLS is not offered |
| Our signalling IPs | from your trunk's page in the dashboard |
| Our media | RTP, UDP `16384–32768`, same IPs |
| Codec | G.711 **A-law (PCMA)**, PCMU as fallback |
| DTMF | RFC 2833 |
| Registration | none — static trunk, authenticated by IP |
| DIDs to route | the numbers you want a Tone agent to answer |

And ask them, explicitly, for three things back:

1. **Their signalling source addresses**, so you can build the `ipAcl`. Not the media addresses —
   they are often different, and an allowlist built from the wrong ones refuses every call.
2. **Their termination host, port and transport** for calls Tone places outbound.
3. **The dialled-number format** they expect: `+91…`, `91…`, or `0…`.

## Create the trunk in Tone

Enterprise trunks are almost always IP-authenticated:

```http
POST /v1/sip-trunks
{
  "name": "Tata Smartflo — HQ",
  "inboundAuth": "ip_acl",
  "ipAcl": ["203.0.113.64/28"],
  "outboundHost": "sbc.smartflo.example",
  "outboundPort": 5061,
  "outboundTransport": "tls",
  "outboundNumberFormat": "national0",
  "callerIdPolicy": "did",
  "codecs": ["PCMA", "PCMU"],
  "maxConcurrent": 30
}
```

`outboundNumberFormat` starts at `national0` here deliberately — Indian enterprise trunks
frequently want `0` + the ten-digit number rather than `+91`. If your first outbound test is
rejected with a number or routing error, that field is the first thing to change; `e164` and
`national` are the other two values.

`ipAcl` entries must be **public IPv4, `/24` or narrower**. Tone refuses private ranges: a
`10.0.0.0/8` in an allowlist is either a typo or a trunk that will never reach us over the public
internet, and both are better caught at write time.

Import each DID:

```http
POST /v1/sip-trunks/{id}/numbers
{ "e164": "+912261234567", "agentId": "…" }
```

## Testing

Do these in order — each one isolates a different half:

1. `POST /v1/sip-trunks/{id}/test` sends `OPTIONS` to their SBC. If this fails, nothing else will:
   it is either the wrong host or a firewall.
2. Call a DID from a mobile — proves their inbound delivery and your `ipAcl`.
3. `POST /v1/calls` on that DID — proves outbound, caller ID and number format, which are the
   three things most likely to still be wrong after inbound works.

## When it does not work

| What you see | Why |
|---|---|
| `OPTIONS` unreachable | Wrong host or port, or Tata has not allowlisted Tone's IPs yet in their direction. |
| Inbound `403` from Tone | Their signalling source is not in your `ipAcl`. Ask for the signalling addresses again — this is the most common single cause. |
| Inbound `404` from Tone | The DID is not imported, or is imported on a different trunk. A DID is only answered on the trunk it was imported on. |
| Outbound rejected | Try `national0`, then `national`. Then check they accept your DID as caller ID. |
| Ringing, then silence | One-way or no media: confirm RTP from Tone's IPs on UDP `16384–32768` is open in their direction, not just SIP. |
| `503` from Tone | The trunk or your organization is at its concurrent-call limit. Raise `maxConcurrent` — and check it does not exceed what your Tata contract allows. |

## A note on caller ID

Tone presents the trunk number in both `From` and `P-Asserted-Identity`. Indian carriers validate
outbound CLI against the numbers on the account, so `callerIdPolicy` should stay `did` unless Tata
has explicitly confirmed they will pass an arbitrary `+91` caller ID for you.