sipx 0.0.6

Modern, high-performance SIP library for Python — httpx-inspired API, async-native, IVR, RTP, DTMF

sipx

A modern, high-performance SIP library for Python inspired by httpx.

Build voice automation scripts, IVR systems, AI-powered call handlers, and SIP testing tools with a clean, Pythonic API.

Features

• httpx-inspired API — client.invite(), client.register(), sync and async
• FastAPI-style server — @server.invite, Annotated DI extractors
• Response builders — request.ok(), request.trying(), request.error(code)
• Dialog tracking — client.ack() / client.bye() without passing response
• Declarative events — @on('INVITE', status=200) decorators
• Full SIP support — 14 methods, auto 100 Trying, auto DNS SRV resolution
• Digest authentication — MD5, SHA-256, auto-retry on 401/407
• RTP + DTMF — RFC 4733 + SIP INFO + Inband, sync and async
• SDP with ICE/SRTP — RFC 4566, offer/answer, ICE candidates, DTLS
• Media pipeline — RTP, tone generators, TTS/STT adapters, IVR builder
• SIP-I — Real ISUP binary encoding (ITU-T Q.763), Brazilian SIP-I (ANATEL)
• Multiple transports — UDP, TCP, TLS, WebSocket (sync + async)
• State management — Transaction FSMs with Timer A/E retransmission
• Extensible — ABC-based transports, body parsers, custom DI extractors

Quick Start

import sipx

# One-liners
sipx.options("sip:pbx.example.com")
sipx.register("sip:[e-mail]", auth=("alice", "secret"))
sipx.send("sip:[e-mail]", "Hello!", auth=("alice", "secret"))

# Full call with dialog tracking
from sipx import Client

with Client(local_port=5061) as client:
    client.auth = ("alice", "secret")

    client.register("sip:[e-mail]")

    sdp = client.create_sdp(port=8000)
    r = client.invite("sip:[e-mail]", body=sdp.to_string())

    if r.status_code == 200:
        client.ack()    # uses tracked dialog
        # call is active...
        client.bye()    # uses tracked dialog

Installation

# With uv (recommended)
uv add sipx

# With pip
pip install sipx

# From source
git clone https://github.com/oornnery/sipx.git
cd sipx
uv sync

Requirements

Python 3.12+

Usage Examples

SIP Server (FastAPI-style decorators + DI)

from typing import Annotated
from sipx import SIPServer, Request, FromHeader, Header

server = SIPServer(local_host="127.0.0.1", local_port=5060)

@server.register
def on_register(request: Request, caller: Annotated[str, FromHeader]):
    print(f"REGISTER from {caller}")
    return request.ok()

@server.message
def on_message(request: Request, caller: Annotated[str, FromHeader]):
    body = request.content.decode() if request.content else ""
    print(f"MESSAGE from {caller}: {body}")
    return request.ok()

server.start()

Async Client

import asyncio
from sipx import AsyncClient

async def main():
    async with AsyncClient(local_port=5061) as client:
        client.auth = ("alice", "secret")

        r = await client.register("sip:[e-mail]")
        print(f"REGISTER: {r.status_code}")

        sdp = client.create_sdp(port=8000)
        r = await client.invite("sip:[e-mail]", body=sdp.to_string())
        if r and r.status_code == 200:
            await client.ack()
            await asyncio.sleep(5)
            await client.bye()

asyncio.run(main())

FastAPI + SIP Integration

Run a REST API that controls SIP operations:

# Terminal 1: SIP server
uv run python examples/server.py

# Terminal 2: FastAPI
uv run python examples/fastapi_sip.py

# Terminal 3: test via curl
curl -X POST http://localhost:8000/message \
  -H "Content-Type: application/json" \
  -d '{"uri":"sip:test@127.0.0.1:15090","content":"Hello from FastAPI!"}' | jq

{
  "status_code": 200,
  "reason": "OK"
}

Full request/response trace with retransmission timers, DI resolution, and FSM state transitions:

# FastAPI (client side)
INFO     UDP bound to 0.0.0.0:40703
DEBUG    Transaction 592b5fee created: MESSAGE (type=NON_INVITE)
DEBUG    Timer E started (0.5s)          # retransmission armed
DEBUG    Timer F started (32.0s)         # timeout armed
DEBUG    UDP send 335 bytes -> 127.0.0.1:15090
DEBUG    UDP recv 245 bytes <- 127.0.0.1:15090
DEBUG    <<< 200 OK
DEBUG    Transaction 592b5fee: TRYING -> COMPLETED
DEBUG    Timer E cancelled               # retransmission stopped
DEBUG    Timer F cancelled               # timeout stopped

# SIP Server (server side)
DEBUG    UDP recv 335 bytes <- 127.0.0.1:40703
DEBUG    Resolving handler on_message
DEBUG    Extracting caller via FromHeader()
  MESSAGE from <sip:user@0.0.0.0>: Hello from FastAPI!
DEBUG    >>> SENDING 200 OK to 127.0.0.1:40703
DEBUG    UDP send 245 bytes -> 127.0.0.1:40703

Event Handlers

from sipx import Events, on

class CallEvents(Events):
    @on('INVITE', status=200)
    def on_call_ok(self, request, response, context):
        print("Call accepted!")

    @on('INVITE', status=(180, 183))
    def on_ringing(self, request, response, context):
        print(f"Ringing... ({response.status_code})")

    @on(status=(401, 407))
    def on_auth(self, request, response, context):
        print("Auth challenge received")

Authentication

# Tuple auth (auto-retry on 401/407)
client.auth = ("alice", "secret")

# Or explicit Auth object
client.auth = Auth.Digest("alice", "secret")

# Per-request override
r = client.register("sip:[e-mail]")
if r.status_code == 401:
    r = client.retry_with_auth(r, auth=Auth.Digest("alice", "other"))

Supported Methods

Method	Description	Example
INVITE	Establish a call	client.invite('sip:[e-mail]', body=sdp)
ACK	Acknowledge INVITE	client.ack() (auto dialog)
BYE	Terminate a call	client.bye() (auto dialog)
CANCEL	Cancel pending INVITE	client.cancel(response=r)
REGISTER	Register location	client.register('sip:[e-mail]')
OPTIONS	Query capabilities	client.options('sip:ex.com')
MESSAGE	Instant message	client.message('sip:[e-mail]', content='Hi')
SUBSCRIBE	Subscribe to events	client.subscribe('sip:[e-mail]')
NOTIFY	Event notification	client.notify('sip:[e-mail]')
REFER	Call transfer	client.refer('sip:[e-mail]', refer_to='sip:[e-mail]')
INFO	Mid-dialog info (DTMF)	client.info('sip:[e-mail]', content=dtmf)
UPDATE	Update session	client.update('sip:[e-mail]', sdp_content=sdp)
PRACK	Provisional ACK	client.prack(response=r)
PUBLISH	Publish state	client.publish('sip:[e-mail]')

RFC Compliance

RFC	Title	Status
3261	SIP: Session Initiation Protocol	Complete (auto 100 Trying, retransmission)
2617	HTTP Digest Authentication	Complete (MD5, SHA-256)
7616	HTTP Digest (SHA-256)	Complete
4566	SDP: Session Description Protocol	Complete (ICE, SRTP, DTLS)
3264	Offer/Answer Model with SDP	Complete
3550	RTP: Real-time Transport Protocol	Complete (sync + async)
4733	DTMF via RTP (telephone-event)	Complete
3263	DNS SRV Resolution	Complete (auto in Client)
4028	Session Timers	Complete

Documentation

Document	Description
docs/SDD.md	Software Design Document (full spec, diagrams, roadmap)
examples/README.md	Examples catalog (22 examples)
docker/asterisk/	Asterisk test environment

Testing with Asterisk

cd docker/asterisk
docker-compose up -d
uv run python examples/asterisk.py

Examples

See examples/README.md for the full list. Highlights:

Example	What it shows
quickstart.py	One-liner register, options, call, send
call.py	REGISTER -> INVITE -> ACK -> BYE
server.py	SIPServer with decorators + DI
ivr.py	Async IVR with RTP + DTMF
response_builders.py	request.ok/trying/error, dialog tracking
asterisk.py	Comprehensive integration test

Roadmap

See docs/SDD.md for the full roadmap. Key upcoming work:

• SRTP — packet encryption (RFC 3711)
• RTCP — control protocol (RFC 3550 Section 6)
• Jitter buffer — for smooth RTP playback
• Coverage >80% — currently 607 tests, ~60%
• PyPI publishing — package ready, CI pipeline configured

Development

git clone https://github.com/oornnery/sipx.git
cd sipx
uv sync
uv run ruff check sipx
uv run pytest

Inspirations

API design:

• httpx — Pythonic API, sync/async, extensible

Reference implementations:

• sipd — SIP daemon implementation
• sipmessage — SIP message parsing
• sip-parser — SIP parser
• PySipIvr — SIP IVR implementation
• sip-resources — Curated SIP resources and documentation

Other inspirations:

• pyVoIP — VoIP functionality
• aiosip — Async SIP
• b2bua — Back-to-back user agent
• pysipp — SIP testing
• PySIPio — SIP I/O
• katariSIP — SIP library
• SIP-Auth-helper — SIP auth tools
• callsip.py — Simple SIP caller

License

MIT License