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## Brief: Multi-Tenant WebRTC-to-SIP Bridge for Asterisk Trunks Build a SIP gateway service that bridges WATI WhatsApp Calls API WebRTC media/signalling to standard SIP trunks usable by Asterisk. The system must support multiple tenants, where each tenant can have one or more WATI WebRTC endpoints mapped to one or more SIP trunks on Asterisk. The WATI integration uses SDP exchange over authenticated HTTPS APIs. WATI provides inbound call webhooks with `callId`, `sdp`, and `businessNumber`, and requires the bridge to generate a WebRTC SDP answer and POST it to `/calls/{callId}/accept`. Outbound calls require permission handling, SDP offer generation, and POST to `/calls/outbound-call/{waid}`. WATI requires Bearer-token authentication, Opus audio, complete ICE gathering without trickle ICE, and public webhooks that return HTTP 200 within 30 seconds. ### Required Architecture **Core components** 1. **Tenant Manager** * Stores tenant ID, WATI API base URL, WATI bearer token, webhook API key, business numbers, SIP trunk mappings, routing rules, and limits. * Supports multiple WATI accounts and multiple business numbers per tenant. 2. **Webhook API** * Public HTTPS endpoints for: * New inbound call * Terminate call * New outbound call/connect * Outbound call status * Call permission reply * Verifies WATI webhook `Authorization: Bearer {ApiKey}`. 3. **WebRTC Signalling Engine** * Handles WATI SDP offer/answer exchange. * Creates WebRTC peer connections. * Forces audio-only Opus. * Disables trickle ICE and sends complete SDP only. * Normalises SDP fingerprints to uppercase where required. 4. **SIP Gateway** * Presents each mapped WATI endpoint as a SIP trunk/peer to Asterisk. * Supports SIP registration or static IP trunking. * Converts SIP INVITE/200 OK/BYE to WATI call API actions. * Bridges RTP/SRTP media between SIP/RTP and WebRTC/DTLS-SRTP. 5. **Media Relay** * Transcodes only if required, but preferred codec path is Opus end-to-end. * Supports RTP, SRTP, ICE, DTLS, NAT traversal, STUN/TURN. * Maintains per-call media sessions. 6. **Routing Engine** * Inbound: `businessNumber` or WATI tenant maps to SIP trunk, DID, extension, queue, or Asterisk context. * Outbound: SIP trunk or caller ID maps to WATI tenant, business number, and WhatsApp destination `waid`. * Allows one-to-one, many-to-one, and many-to-many mappings. ### Call Flows **Inbound WhatsApp to Asterisk** WhatsApp user calls business number → WATI sends inbound webhook → bridge identifies tenant and trunk → bridge creates WebRTC answer → bridge accepts call via WATI API → bridge sends SIP INVITE to Asterisk trunk → media flows between WebRTC and SIP RTP. **Outbound Asterisk to WhatsApp** Asterisk sends SIP INVITE to bridge trunk → bridge identifies tenant/trunk mapping → bridge checks WhatsApp call permission → bridge creates WebRTC SDP offer → bridge calls WATI outbound call API → WATI returns `callId` → bridge waits for outbound connect webhook with SDP answer → media session starts → SIP 200 OK returned to Asterisk. ### Multi-Tenant Requirements Each tenant must have isolated: * WATI credentials * webhook API keys * SIP trunk credentials * routing rules * call records * call limits * logs * media sessions * rate limits The platform must allow: * Multiple SIP trunks per tenant * Multiple WATI business numbers per tenant * Multiple WATI tenants on one server * Per-trunk inbound and outbound routing * Per-tenant authentication and call accounting ### Asterisk Trunk Requirement Asterisk must be able to add each bridge endpoint as a normal SIP/PJSIP trunk, for example: ```ini [wati-tenant-001] type=endpoint transport=transport-udp context=from-wati disallow=all allow=opus,ulaw,alaw aors=wati-tenant-001 auth=wati-tenant-001-auth direct_media=no rtp_symmetric=yes force_rport=yes rewrite_contact=yes ``` ### Security Requirements * HTTPS only for WATI webhooks * SIP authentication per trunk * IP allowlisting where possible * Encrypted storage for WATI bearer tokens * Webhook bearer validation * Per-tenant rate limiting * Full audit logging * No token exposure in logs * Optional TLS/SRTP for SIP side ### Deliverables 1. Multi-tenant WebRTC-to-SIP gateway 2. Admin configuration for tenants, trunks, WATI credentials, and routing 3. Public webhook endpoints for WATI 4. SIP trunk listener for Asterisk 5. Media relay between WebRTC and SIP RTP 6. Call permission management for outbound WhatsApp calls 7. CDR and call-status logging 8. Deployment scripts for Debian 9. Example Asterisk trunk configuration 10. Production hardening guide with DNS, SSL, firewall, and monitoring requirements
Project ID: 40542253
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Hello, your WATI to Asterisk SIP gateway requires a solid WebRTC-to-SIP bridge with proper tenant isolation and real-time media handling. I can design and implement the full architecture including webhook APIs, SDP exchange, SIP trunk integration, routing engine, and secure multi-tenant structure with logging and rate limits. Do you already have an existing Asterisk setup and SIP trunk provider, or should I design the full deployment stack as well? Hope to work with you on this!
$115 USD in 2 days
4.0
4.0
31 freelancers are bidding on average $131 USD for this job

As an accomplished python web automation specialist with over 13 years of experience, I assure you of my ability to deliver tailored, result-oriented solutions - crucial attributes for this complex multi-tenant task. My comprehensive skills in Python, paired with a keen interest in utilizing it for high-impact projects is an ideal fit for your WhatsApp-to-Asterisk SIP Gateway. Among the many notable projects i've recently completed, my most recent work includes a similar project developed for a car rental company where I built a sophisticated and dynamic website that integrated several services. Additionally, my extensive skillset also covers Web3 and Blockchain Development which enables me to approach tasks like these from multiple angles for an even more efficient delivery. Security being paramount, I assure HTTPS-only implementations for WATI webhooks and strictly adhere to secure coding conventions and best practices. In choosing me to bring your project to life, you can be assured of not only the highest level of technical expertise but also solid communication and timely updates throughout our journey together. Looking forward to discussing your project further.
$30 USD in 1 day
5.7
5.7

Hi, WebRTC-to-SIP bridging on Asterisk is something we've done a few times now, check out our recent work at securetechs.io. For this I'd start by setting up the Asterisk trunk configuration with proper SIP authentication and codec negotiation, then build the WebRTC signaling layer to handle WATI's incoming sessions and translate them to SIP INVITE flows. Multi-tenant isolation would be handled at the trunk level with separate credentials per tenant. I'll also set up a lightweight database to track active sessions and call state so nothing gets dropped mid-call. You'll get a working demo environment to test against before anything goes to production. Can have a functional prototype in 3 days. Regards, Imtiaz, SecureTechs
$75 USD in 5 days
3.6
3.6

Hi, I’m ready to start immediately. I have 8+ years of experience building VoIP, SIP, WebRTC, and backend systems using Python, Node.js, FastAPI, Asterisk, and cloud deployments. I can develop your multi-tenant WebRTC-to-SIP gateway with WATI integration, secure webhook handling, SDP/ICE negotiation, RTP bridging, PostgreSQL, routing engine, and production-grade security. I’ll deliver clean, scalable code, deployment scripts, documentation, and ongoing support. I’m confident I can build a reliable, production-ready solution for your requirements.
$140 USD in 7 days
2.3
2.3

Hello! I’ve built a multi-tenant WebRTC-to-SIP bridge for a similar setup, resulting in a 30% reduction in latency and improved call quality. I’d love to share the implementation details with you in chat. To tackle your project, I'd focus on creating a robust Tenant Manager for configuration, followed by a WebRTC Signalling Engine that ensures seamless media handling. Given the need for security, I’d prioritize strong authentication and rate limiting for each tenant. One question I have is: how do you plan to handle scaling if you anticipate a significant number of concurrent calls? If you’re open, I can share the similar build, and we can see if it fits your needs.
$140 USD in 7 days
1.6
1.6

✅✅✅✅Hi, there.✅✅✅✅ I can seamlessly develop a Multi-Tenant WebRTC-to-SIP Bridge for Asterisk Trunks, ensuring seamless integration between WATI WhatsApp Calls API and SIP trunks for Asterisk. This project aligns perfectly with my expertise, and I am eager to discuss how I can bring value to your project. I understand the intricate details of the required architecture, including the Tenant Manager, Webhook API, WebRTC Signalling Engine, SIP Gateway, Media Relay, and Routing Engine, ensuring secure and efficient communication between platforms. Furthermore, I am committed to delivering not just a functional solution but also comprehensive documentation, ensuring scalability and ease of future updates for your team. Best Regards, Oleksandr
$100 USD in 7 days
1.7
1.7

Hello, Bearer-token authentication – you need a secure, per‑tenant webhook handler that validates the token and returns HTTP 200 within 30 seconds, otherwise WATI will drop the call. I'll build the bridge with Node.js + Express, using the 'wrtc' library to generate a full SDP answer in one go, keeping cold‑load latency under 200 ms. Each tenant's WATI credentials will be encrypted at rest (AES‑256) and isolated in PostgreSQL, while Docker containers ensure clean deployment on Debian. I'll also enforce non‑trickle ICE by waiting for complete ICE gathering before sending the SDP, which avoids intermittent media failures that many SIP‑to‑WebRTC adapters encounter. Do you already have Asterisk endpoint definitions you can provide for the SIP trunk mapping? Looking forward to working with you. Artur Giżycki
$130 USD in 3 days
1.2
1.2

Treat the bid amount and timeline above as rough placeholders -- we'll sharpen both once we've talked through the full scope. This is a solid but genuinely tricky piece of infrastructure. You need a bridge that speaks WebRTC on one side (WATI's SDP/ICE model, with all the quirks -- Opus-only, no trickle ICE, 30-second webhook response window) and standard SIP on the other, so Asterisk can treat WATI endpoints as normal trunks. The multi-tenant layer adds the real complexity: each tenant gets its own WATI credentials, business numbers, and SIP trunk mappings, and none of that can bleed into another tenant's calls. Done right, this is a clean, low-latency media path with almost no moving parts at call time. Here's how we'd approach it: - Tenant Manager: PostgreSQL-backed config store with per-tenant WATI base URL, bearer tokens, webhook API keys, business number lists, and SIP trunk mappings. Isolated at the DB row level so one tenant's config can never affect another. - Webhook API: FastAPI (Python) exposing public HTTPS endpoints for inbound call, termination, outbound connect, outbound status, and permission reply. Bearer token verified on every request; responds HTTP 200 within the WATI window before handing off to async processing. - WebRTC Signalling Engine: aiortc for peer connection management, forced Opus audio, full ICE candidate gathering before SDP is sent (no trickle), and SDP fingerprint normalisation to uppercase to satisfy WATI's validation. - SIP Gateway: FreeSWITCH or a lightweight pjsip-based service sits between Asterisk and the WebRTC engine, handling INVITE/200 OK/BYE translation and presenting each WATI endpoint as a registered SIP peer to Asterisk. - Media Relay: DTLS-SRTP on the WebRTC side bridged to plain RTP toward Asterisk, with transcode only where codec mismatch requires it. Coturn for STUN/TURN so ICE works across NAT. After a short call to walk through the tenant setup flow and any Asterisk version constraints, we'll put together a proper written proposal with milestones, deliverables, and a firm price. Want to jump on a quick call this week to walk through the architecture and confirm the Asterisk side of things? Best, 96 Studio
$188 USD in 14 days
1.1
1.1

I can build the multi-tenant WATI-to-Asterisk SIP gateway with the required webhook, signaling, routing, and media-bridge layers. I will design it for isolated tenant credentials, secure call handling, and clean Asterisk trunk interoperability, with production-ready deployment and hardening for Debian. Jared
$155 USD in 3 days
0.0
0.0

Hi, I'd build this in Python using aiortc for the WebRTC layer and a lightweight SIP stack for the Asterisk trunk side, with a PostgreSQL-backed tenant manager handling isolated credentials, routing rules, and CDR per tenant from day one. The key is getting the ICE gathering and complete SDP exchange with WATI right before anything else, because trickle ICE failures are the silent call-killer in WebRTC-to-SIP bridges and WATI's 30-second webhook deadline leaves no room for incomplete negotiation, is the goal. In similar projects, I've built WebRTC media bridges where the DTLS-SRTP to RTP conversion and NAT traversal logic required the most careful testing before the SIP signalling side even came into play. You'll get all ten deliverables including the multi-tenant gateway, webhook endpoints, Asterisk PJSIP trunk configuration, media relay, CDR logging, Debian deployment scripts, and a production hardening guide. Share your WATI sandbox credentials and I'll confirm ICE and SDP compatibility before full development begins.
$50 USD in 7 days
0.0
0.0

Hi there, I just read your posting. It sounds like you need an experienced software engineer who can help build, improve, and maintain a reliable solution using WebRTC, Security, Network Security, Cloud Computing, SIP, Linux, Database Management and API Development. I am a software engineer with 12+ years of experience designing and developing web, cloud, automation, and enterprise applications. I specialize in building scalable, maintainable, and production-ready solutions while ensuring high code quality, performance, security, and long-term stability. I can help review your requirements, identify the most effective technical approach, and implement the solution professionally. Whether the work involves backend development, frontend development, API integrations, cloud infrastructure, databases, automation, AI solutions, troubleshooting, performance optimization, or system architecture, I can help deliver the project successfully. I focus on clear communication, clean code, and practical solutions that align with business goals. My objective is not only to complete the immediate task but also to create a solution that is easy to maintain and extend in the future. Let me know if my profile looks interesting, and we can set up a time to talk. Best regards, Elijah M.
$200 USD in 3 days
0.0
0.0

Hello, I'd be thrilled to assist with your project, leveraging my expertise in building robust multi-tenant systems. With experience in handling complex SIP integrations, SDP exchange, and WebRTC protocols, I am well-equipped to address the challenges of bridging WATI WhatsApp Calls API WebRTC to SIP trunks on Asterisk. Here's how I'll approach your project: ✔ Develop a secure, scalable multi-tenant WebRTC-to-SIP gateway ✔ Implement tenant management features for WATI credentials, SIP trunk mappings, and routing rules ✔ Create Webhook API endpoints for seamless integration with WATI ✔ Establish SIP gateway services for Asterisk interoperability ✔ Ensure efficient media relay between WebRTC and SIP RTP for optimal call quality ✔ Manage call permissions and logging effectively ✔ Provide detailed deployment scripts for Debian systems My goal is to deliver a reliable, polished solution that meets your requirements seamlessly. Best regards, Manthan
$100 USD in 14 days
0.0
0.0

As a seasoned software developer with in-depth expertise in API development, your project aligns perfectly with my skillset. Not only do I excel at building robust multi-tenant architectures like the one you've specified, but my AI-first approach ensures that the systems I design are intelligent, efficient, and most importantly, meet your business needs head-on. Throughout my career, I've embraced the challenge of delivering tailored solutions to diverse and demanding clients like yourself. I prioritize end-to-end ownership - from planning to deployment to support, ensuring maximum value at every stage of the project. My work stands out for its clean, scalable architecture built to accommodate future growth - a critical requirement for your multi-tenant platform. In conclusion, working with me means leveraging years of experience in full-stack web and SaaS product development alongside handling complex third-party integrations. Your project isn't just another programming assignment for me; it's an opportunity to create massive impact through automation and smart system architecture. Let's build an AI-powered solution that revolutionizes your communication needs!
$100 USD in 5 days
0.0
0.0

Hey, I'm really pumped about this opportunity! I recently led a project with similar challenges and nailed it. Drawing from my experience in Linux, Cloud Computing, Security, Network Security, Database Management, API Development, SIP, WebRTC, I’m ready to dive into your project. Please initiate a chat for further discussion. Kind regards, Vishal Maharaj
$250 USD in 5 days
0.0
0.0

⭐⭐⭐⭐⭐ Hi, I’ve recently worked on real-time communication and SIP/WebRTC integration systems where the main focus was building stable signalling bridges, handling SDP negotiation correctly, and ensuring low-latency media flow between different telecom protocols under production load. From your requirements, this is not a standard API integration — it is a full multi-tenant telecom bridge between WATI’s WebRTC-based WhatsApp calling system and Asterisk SIP trunks. The most critical engineering challenges are correct SDP offer/answer handling without trickle ICE, stable RTP media relay, and maintaining synchronized call state across two different signalling environments under real-time conditions. My approach would be to design a secure multi-tenant core first (tenant isolation, credentials, routing rules, call state tracking), then build a WebRTC signalling engine that fully manages WATI call flows, followed by a SIP/PJSIP gateway layer that exposes each tenant as a standard Asterisk trunk. Media handling would be designed around a low-latency RTP relay with strict session control and Opus-first negotiation to ensure audio quality and stability. With your system requirements and my experience in real-time telecom architecture, we can build a production-ready gateway that behaves like a native SIP trunk while fully supporting WATI’s WebRTC constraints and scaling cleanly across multiple tenants. Thanks, Jessica
$50 USD in 4 days
0.0
0.0

Hi, I have carefully reviewed your detailed project to build a multi-tenant WebRTC-to-SIP bridge for WATI WhatsApp Calls API integrating seamlessly with Asterisk trunks. With experience in API Development, Database Management, and WebRTC protocols, I am confident in architecting a secure and scalable gateway that manages isolated tenants, handles SDP exchanges, and enforces call permissions. I will ensure HTTPS webhook security, SIP authentication, and Opus codec consistency while providing robust tenant management and real-time call logging. Together, we will achieve reliable media relay, precise routing, and full auditability with deployment scripts tailored for Debian. Let's discuss your timeline and next milestones to start crafting this innovative communication bridge. How do you envision scaling the multi-tenant WebRTC-to-SIP gateway to accommodate growing call volumes while maintaining performance and security? Thanks,
$155 USD in 17 days
1.0
1.0

The multi-tenant isolation is the tricky part here. Each tenant needs its own SIP credentials and call routing so traffic never bleeds across accounts. I would build this in Node.js with an Asterisk ARI layer handling the WebRTC-to-SIP bridge per tenant. Can start today and have the core gateway working in 4 days. The bid reflects what's in the description. Once we walk through the full scope, the number may adjust. Want to jump on a quick call?
$150 USD in 14 days
0.0
0.0

Hi, there. I’ve worked with Asterisk/PJSIP, SIP signaling, WebRTC SDP, ICE/STUN/TURN, RTP/SRTP, authenticated webhooks, and multi-tenant backend systems. I understand this is not a basic webhook integration. The bridge must keep SIP and WATI call states synchronized, gather complete non-trickle ICE, enforce Opus, bridge WebRTC/DTLS-SRTP to SIP/RTP, and correctly handle accept, connect, terminate, BYE, and permission events. My proposed stack: * Go or Node.js signaling/control service * PostgreSQL for tenants, routes, trunks, and CDRs * Redis for active calls and rate limits * rtpengine or FreeSWITCH for media relay * WATI webhook/API adapter * SIP trunk interface for Asterisk * Encrypted credentials, audit logs, and tenant isolation * Debian deployment scripts and example PJSIP config I would begin with a POC covering one inbound and one outbound call using one WATI number and one Asterisk trunk. Once SDP, media, permissions, and teardown are proven, I would extend it to full multi-tenant routing. I’ll need WATI sandbox/API access, sample webhook payloads, Asterisk version, TURN details, and expected concurrent calls.
$140 USD in 7 days
0.0
0.0

**DO NOT PAY ME UNTIL I COMPLETE! :)** Hello my valuable client :) I've got 7 years of experience and fully understand what you're looking for—I can definitely hit your timeline. I'll also throw in a year of free maintenance after we're done, and honestly, if you're not happy with the work, don't pay me at all. Just shoot me a message when you're ready and let's get started. I am eagerly waiting for your message. Roman
$50 USD in 1 day
0.0
0.0

Hi there, I've thoroughly reviewed your project requirements for building a Multi-Tenant WebRTC-to-SIP Bridge for Asterisk Trunks. I understand the complexity of integrating WATI WhatsApp Calls API with WebRTC and SIP trunks on Asterisk while ensuring multi-tenancy support and security. With my extensive experience in developing custom SIP gateways and WebRTC solutions, I am confident in delivering a robust and scalable system that meets your specific needs. I have successfully completed similar projects involving real-time communication technologies and multi-tenant architectures. To tackle this project, I propose a phased approach: - Setting up a secure multi-tenant architecture with isolated resources for each tenant - Implementing the necessary components such as Tenant Manager, Webhook API, WebRTC Signalling Engine, SIP Gateway, Media Relay, and Routing Engine - Ensuring seamless integration between WATI, WebRTC, and Asterisk trunks - Emphasizing security measures like HTTPS, SIP authentication, and encryption - Providing comprehensive admin configuration tools and deployment scripts for easy management I am excited about the opportunity to discuss how we can bring your project to life and address any specific requirements you may have. Let's connect to explore the project details further. Looking forward to the possibility of collaborating with you. Filip
$350 USD in 7 days
0.0
0.0

"We've just completed a similar project where we developed a multi-tenant WebRTC-to-SIP gateway service for seamless communication integration. We'll help you achieve a robust SIP gateway service bridging WATI WhatsApp Calls API WebRTC media to standard SIP trunks usable by Asterisk. Understanding your need for a clean, professional, and integrated solution, we specialize in developing secure, user-friendly systems with encrypted storage, per-tenant rate limiting, and full audit logging. Our expertise lies in building multi-tenant architectures, WebRTC signaling engines, SIP gateways, media relay systems, and routing engines to ensure a seamless communication experience. I'd love to chat about your project! The worst that could happen is you walk away with a free consultation. Regards, Keagon."
$150 USD in 7 days
0.0
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