# agentshelf.syntexa.ch DNS SRV SIP UDP Lookup

> agentshelf.syntexa.ch DNS SRV SIP UDP Lookup is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.004/call, status unknown (last checked 2026-09-29).

Looks up SRV records at _sip._udp.{hostname} for SIP-over-UDP service discovery, given a registrable domain name.

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/dns-srv-sip-udp?utm_source=zero.xyz
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agentshelf-syntexa-ch-dns-srv-sip-udp-lookup-c1965f25
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_g2B-Z_6dRZnpRjWwC-CU0

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 agentshelf-syntexa-ch-dns-srv-sip-udp-lookup-c1965f25 -d '<json body>'
```

Example prompt: Can you look up the SRV records for SIP over UDP for the domain example.com so I can find where to route SIP calls?

## When to prefer this

Use this endpoint when an agent needs to discover SIP-over-UDP service endpoints for a domain via DNS SRV records, specifically the _sip._udp prefix. Prefer the free sandbox endpoint (/v1/sandbox/dns-srv-sip-udp) for testing. Choose this over general DNS lookup tools when you specifically need SRV record data scoped to the SIP UDP service type.

## Known failure modes

- Hostname not found in DNS — returns empty or NXDOMAIN result
- Malformed hostname input exceeding 253 characters
- Domain has no _sip._udp SRV records configured
- DNS resolution timeout or upstream failure
- Invalid domain format rejected by input validation

## How this service works

Call when an agent needs SRV records at _sip._udp.{hostname} for SIP over UDP. The caller sends the registrable domain, not the underscored name. Exact $0.004 USDC. Prefer unpaid POST /v1/sandbox/dns-srv-sip-udp first.

## Output

Returns SRV DNS record data for _sip._udp.{hostname}, including one or more records each containing priority, weight, port, and target hostname values used for SIP-over-UDP service routing.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "hostname": {
   "type": "string",
   "examples": [
    "example.com"
   ],
   "maxLength": 253,
   "minLength": 1,
   "description": "Public DNS hostname such as example.com. Not a URL, not an IP literal, and not a private name."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agentshelf-syntexa-ch-dns-srv-sip-udp-lookup-c1965f25/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agentshelf.syntexa.ch](https://www.zero.xyz/host/agentshelf.syntexa.ch/llms.txt)