# SIP TCP SRV Record Lookup

> SIP TCP SRV Record Lookup is a paid API for AI agents from dns.intel.rallylive.ca, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-22).

Looks up _sip._tcp SRV DNS records for a domain to discover SIP service host, port, priority, and weight via Cloudflare DoH.

## Facts

- Endpoint: GET https://dns.intel.rallylive.ca/dns/srv/sip-tcp?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-22
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/sip-tcp-srv-record-lookup-85ef8797
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_AVUX-T5o3ucc02HiVER-J

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability sip-tcp-srv-record-lookup-85ef8797
```

Example prompt: Can you look up the _sip._tcp SRV records for example.com so I know which host and port handle its SIP service and what the priority and weight are?

## When to prefer this

Choose this endpoint when you need to programmatically discover where a domain's SIP TCP service lives, including host, port, priority, and weight, without manually guessing hostnames. It is ideal for VoIP client configuration, telecom infrastructure auditing, SIP trunk setup, and automated failover routing. It specifically targets _sip._tcp (TCP transport) as opposed to _sip._udp (UDP transport).

## Known failure modes

- Domain has no _sip._tcp SRV records — returns empty result set
- Domain does not exist (NXDOMAIN) — lookup fails with DNS error
- Cloudflare DoH upstream timeout — transient error requiring retry
- Malformed domain input — query rejected
- SERVFAIL from authoritative DNS — upstream DNS error propagated

## How this service works

SIP service discovery (_sip._tcp.<domain>): SRV records with priority, weight, port and target host, from Cloudflare DoH. Tells a client where the domain's sip service lives without guessing hosts. $0.01 per lookup.

## Output

Returns one or more SRV records for the _sip._tcp.<domain> DNS query, each containing: priority (integer), weight (integer), port (integer), and target hostname. Multiple records may be returned when the domain has multiple SIP endpoints for load balancing or failover.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {}
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/sip-tcp-srv-record-lookup-85ef8797/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from dns.intel.rallylive.ca](https://www.zero.xyz/host/dns.intel.rallylive.ca/llms.txt)