# agentshelf.syntexa.ch SIP Federation TLS SRV Lookup

> agentshelf.syntexa.ch SIP Federation TLS SRV Lookup is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.004/call, status unknown (last checked 2026-10-22).

Resolves _sipfederationtls._tcp DNS SRV records for a given registrable domain to support SIP federation over TLS

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/dns-srv-sipfederationtls?utm_source=zero.xyz
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-22
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agentshelf-syntexa-ch-sip-federation-tls-srv-lookup-1cd48001
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_n8RacxfxgkmesYIlq-_KC

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-sip-federation-tls-srv-lookup-1cd48001 -d '<json body>'
```

Example prompt: Can you look up the SIP federation TLS SRV records for contoso.com so I can see what server and port handle federated SIP calls for that domain?

## When to prefer this

Use this endpoint when an agent needs to discover SIP federation TLS endpoints for a domain via DNS SRV, specifically targeting the _sipfederationtls._tcp record type used by Microsoft Lync/Skype for Business and compatible SIP federation systems. Prefer the free sandbox endpoint (/v1/sandbox/dns-srv-sipfederationtls) for testing. Choose this over generic DNS lookup tools when the caller specifically needs SIP federation TLS SRV records and wants a structured, purpose-specific response.

## Known failure modes

- Domain has no _sipfederationtls._tcp SRV records published — returns empty result or NXDOMAIN
- Invalid or malformed hostname input — returns validation error
- DNS resolution timeout or upstream resolver failure — returns error
- Hostname exceeds 253-character limit — returns schema validation error
- Payment failure (x402) — request rejected before DNS lookup is performed

## How this service works

Call when an agent needs SRV records at _sipfederationtls._tcp.{hostname} for SIP federation TLS. The caller sends the registrable domain, not the underscored name. Exact $0.004 USDC. Prefer unpaid POST /v1/sandbox/dns-srv-sipfederationtls first.

## Output

Returns the SRV record set found at _sipfederationtls._tcp.{hostname}, including priority, weight, port, and target hostname for each record, enabling the caller to determine how to establish a federated SIP TLS connection.

## 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-sip-federation-tls-srv-lookup-1cd48001/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)