Cross-Platform SIP & WebRTC Softphone App Build (iOS & Android)

@infowider11

***** Production-Ready SIP & WebRTC Softphone (iOS & Android) ***** I can deliver a production-grade softphone built with (iOS) and Compose (Android), leveraging WebRTC for media and SIP (UDP/TLS) for signalling, fully compatible with your hosted PBX. The app will support on-device audio mixing for ad-hoc conferencing, BLF, transfer, hold/resume, DTMF, visual voicemail, two-way SMS, call quality metrics (MOS/jitter/packet loss), push notifications (APNs/FCM), and a polished corporate UI aligned with your brand. • SIP registration (UDP & TLS) • WebRTC media handling • Username/password authentication • PBX onboarding configuration • On-device audio mixing (conference/merge) • Ad-hoc conferencing • Call transfer (blind & attended) • Call hold and resume • DTMF support • BLF (Busy Lamp Field) • Visual voicemail (play, delete, download) • Two-way SMS messaging • Push notifications (APNs & FCM) • Call quality statistics (MOS, jitter, packet loss) • Contact list (local & hosted) • Recent call history • In-app web browser view • Background call handling • STUN/TURN configuration support • Secure credential Hhstorage • Branded corporate UI • Call logs and troubleshooting view Let’s chat… Thanks

@AwaisChaudhry

Hello, I will build a production-ready Cross-Platform SIP & WebRTC Softphone for iOS and Android, tightly matching your corporate UI and branding. The app will use WebRTC for media and SIP over UDP/TLS for signaling, with push notifications for inbound calls/messages, on-device audio mixing for conferencing, ad-hoc merge/BLF/DTMF, and features like transfer, visual voicemail, two-way SMS, contact lists, call history and a web view to show your webpage. Deliverables include native builds (SwiftUI for iOS, Kotlin/Jetpack Compose for Android) ready for TestFlight and internal testing, a complete well-commented private source repo, a configuration guide (SIP domains, STUN/TURN, push keys, assets) and a QA checklist. I’ll provide a clear project plan, milestones, risk mitigation and a demo against your Hosted PBX. One crucial clarifying question for the client to kick off the project: What is the preferred approach for user authentication and onboarding (username/password against your PBX or a separate onboarding flow for new customers) and how will this integrate with existing identity management? Questions I’d ask to ensure a smooth delivery: 1) Which PBX server and SIP profiles should we support (SIP over TLS only or UDP too)? 2) Do you require SFU-based mixing or on-device only, and what is the target maximum participants per conference? 3) What push certificate management approach do you prefer for APNs/FCM? 4) Any specific codecs (e.g., Opus, G722) or bandwidth constraints

@irsolutions

With over 10 years of experience in web and mobile development, specializing in cross-platform app development, I understand the key requirements of your project for a Cross-Platform SIP & WebRTC Softphone App Build for iOS and Android. The challenge of implementing local audio mixing and other advanced features while maintaining a polished UI aligns perfectly with my expertise. In the realm of FinTech and Communication Technology, I have successfully delivered projects similar to yours, ensuring seamless communication solutions for businesses. My past successes in implementing SIP and WebRTC functionalities have driven tangible results for my clients, with a focus on user-friendly interfaces and reliable performance. I am eager to bring my skills and experience to your project, delivering a high-quality softphone app that meets your specifications. Let's collaborate to create a robust solution that enhances communication and productivity for your organization. I look forward to discussing the project details further and demonstrating how my expertise can benefit your project. Let's turn your vision into reality.

@diektech

Hi, This is Elias from Miami. I’ve reviewed your scope and understand you need a production-ready cross-platform softphone that combines SIP signalling (UDP + TLS) with WebRTC media, plus a polished corporate UI. The hardest requirement is local on-device audio mixing for merged/conference calls (since the server won’t mix), and acceptance is based on lab tests against your Hosted PBX + a live demo with two concurrent handsets. I can support the build end-to-end (iOS + Android) with push for inbound calls/messages (APNs/FCM), BLF, hold/resume, DTMF, attended/blind transfer, visual voicemail, two-way SMS threads, contact sources (local + hosted), recents, an embedded web view, and call quality stats (MOS/jitter/packet loss). -Q1 Which SIP stack is mandated (PJSIP, baresip, custom) and do you require CallKit (iOS) / ConnectionService (Android) for native call UX + background behavior? -Q2 For two-way SMS: is it SIP MESSAGE, PBX API, or a separate SMS provider (and how do you map conversations to identities/DIDs)? -Q3 For local mixing: do you need true multi-party mixing on-device (N>2) or only 2-call merge, and are there codec constraints (Opus/G.711) we must support? Thanks.

@planDapps

HIGH AVAILABILITY SOFTPHONE: NATIVE AUDIO MIXING & REAL TIME WEBRTC SIGNALING Hi, Developing a softphone that rivals Acrobits requires precise handling of signaling and low level audio buffers. At Plan D Studios, we bring 12+ years of experience in mobile app development and custom software, with deep expertise in VoIP, SIP, and WebRTC architecture. Our Technical Approach: Local Audio Mixing: We utilize native audio units and Oboe/AAudio to perform on device PCM mixing for conference calls, solving your server side limitation. Hybrid Connectivity: We implement SIP (UDP/TLS) for signaling and WebRTC for media, integrated with CallKit and ConnectionService for seamless iOS development and Android app development. Enterprise Features: Full support for BLF, visual voicemail, two way SMS, and real time MOS/jitter analytics. Architecture: We recommend Flutter or React Native with custom native modules for the media engine to ensure a polished UI with zero performance lag. We do NOT outsource. Our in house team handles the entire API integration and software architecture. We have successfully deployed several SIP based tools and can provide technical demos upon request. Which SIP stack or library (e.g., PJSIP) do you currently prefer for your PBX environment? Let’s build your softphone. Regards, Haider

@technosystem

I am Sushil Kumar Singh, an experienced mobile app developer with an impressive track record in building robust, secure and user-centric Android and iOS applications. I am well-versed in using various frameworks and languages such as Kotlin, Jetpack Compose, Swift and SwiftUI. This makes me the perfect fit for your demands for a softphone with WebRTC and SIP capabilities across both platforms. With my skills in Android, iPhone, Mobile App Development and React Native, I am proficient at delivering cross-platform apps that are highly functional and reliable. My familiarity with the WebRTC and SIP domain will allow me to confidently tackle all your desired features, from conferencing and merged calls to BLF, hold/resume functionalities to name a few. Moreover, my commitment to providing a polished, professional user interface aligned with your brand's aesthetic preferences will ensure the app is not only easy to use but also has elegant typography, a restrained color palette and unobtrusive icons. The end product will truly resonate with your target audience while maintaining harmony across your product line. So let me assure you that as you entrust this project to me, you'll receive exactly what you desire - a production-ready softphone that exceeds your expectations.

@ciss26

Hello, I hope you are doing well. I understand that you are looking to build a MOBILE APPLICATION and I would be happy to help. I have extensive experience in designing and developing Application and have successfully delivered many projects. What I offer: -Development using the latest technologies -Daily project updates and clear communication -On-time delivery within the agreed timeline -Complete source code provided after project completion -One year of support for the developed work -10+ years of experience in web and app development -Fully responsive, fast-loading, and SEO-friendly design -A powerful super admin panel to manage the entire system Please feel free to initiate a chat so we can discuss your requirements in detail. Thank you and regards, Dheeraj K.

@pinkeegupta

Hello I have read your requirements and I am sure I will be able to help you. Please message me so that we will have detail technical discussion. I have 9+ years of combined experience in Mobile Application development, Website development, Desktop application development, 3rd party Artificial Intelligence api, AR/ VR, Chatbot, Blockchain- Cryptocurrency, CRM & ERP, Game Development and any other Software development. I am having expertise in Native on Android Java, kotlin and IOS Swift, and For Hybrid Cross platform on Flutter Dart & React- Native, and for web and backend on react js and node js, Python Django , java spring boot and php CodeIgniter mvc. Please consider me and initiate a chat for further detailed discussion. Regards, Anju

@tahasohail763

This is a production-level softphone project and requires strong telephony architecture, not just mobile development. I understand the need to combine SIP for signaling and WebRTC for media, while implementing local on-device audio mixing for merged and conference calls, which will be the most critical part since your server does not handle mixing. I would structure the app with clear separation between signaling, media handling, and UI, ensuring stable call flows including transfer, hold/resume, DTMF, BLF, voicemail, and two-way SMS. Push notifications via APNs and FCM would be configured for reliable inbound call and message handling. Call quality metrics such as MOS, jitter, and packet loss can be exposed for troubleshooting. The UI would follow a clean, corporate design aligned with your brand. The final delivery would include production-ready builds for iOS and Android, well-documented source code, configuration instructions for SIP and STUN/TURN setup, and a QA checklist validated against your Hosted PBX. I would be happy to review your PBX environment and discuss technical details before starting.

@LiveExperts

Hello, With a comprehensive range of skills encompassing Android, Flutter, and iOS development, my team at Live Experts LLC is more than equipped to deliver a top-quality cross-platform SIP & WebRTC softphone app. We understand the intricate nature of this project and the challenges involved, especially when it comes to local audio mixing for conferenced/merged calls. Rest assured, our extensive experience in machine learning, artificial intelligence, algorithms, and software engineering positions us excellently for this task. I completely comprehend the significance of crafting a user-friendly interface that aligns with your brand values. My knowledge in UNREAL, 3D, AR, VR, Unity 3D, and IOS/Android app development can greatly contribute to providing that polished and professional look you desire. Furthermore, I'm adept at accommodating push notifications (APNs & FCM) for inbound calls and messages, which are crucial elements of a softphone app. My strengths are not just limited to building the app itself: we provide thorough documentation on configuration guides and offer complete well-commented source codes for transparent communication. To ensure maximum satisfaction with our product, we'll even provide a quick start QA checklist. In conclusion, my team offers a combination of technical expertise,prior experience with similar apps using SIP & WebRTC and an unwavering commitment to client satisfaction. Let's discuss your project Thanks!

@mahig47

Hello! As per your project post, you’re looking to build a production ready cross platform SIP and WebRTC softphone app for iOS and Android that connects with your existing PBX, supports advanced calling features, and delivers a polished corporate grade user experience. The goal is to provide reliable voice communication, conferencing, messaging, and voicemail while ensuring high call quality and seamless integration with your telephony infrastructure. My focus will be on developing a robust softphone solution featuring: secure SIP and WebRTC calling with transfer, hold, merge, and conferencing with on device audio mixing, integrated SMS and visual voicemail with playback and management, push notifications for calls and messages, and professional UI with call history, contacts, and browser integration. The platform will ensure stable performance, excellent call quality, and full compatibility with your PBX environment. I specialize in building real time communication apps using Flutter and native modules with SIP, WebRTC, and VoIP push integration, with focus on performance, reliability, and seamless user experience. My focus will be on delivering a production ready softphone with proper native handling for audio mixing and call management. I am confident I can deliver a secure, professional, and fully functional softphone app tailored to your requirements. Best regards, Nikita Gupta.

@hireageek

Hi there, I'm excited about the opportunity to build your cross-platform SIP and WebRTC softphone app for both iOS and Android. As a top freelancer from California with numerous successful projects, I have extensive experience creating user-friendly applications that integrate both SIP and WebRTC technologies seamlessly. I fully understand your requirements for a polished interface, audio mixing, and comprehensive functionality, ensuring the app aligns with your corporate branding and user expectations. In previous projects, I have developed similar applications that included features such as ad-hoc conferencing, visual voicemail, and push notifications, providing a solid foundation for your project. I will ensure that the app supports key functionalities, including two-way SMS and call quality statistics, all while maintaining high performance and reliability. I’m ready to share examples of my work, including demos and code samples, and I believe we can create a top-notch softphone that meets your needs. Please message me today to discuss next steps and timelines. What specific features are your highest priority for the initial release of the softphone?

@GameOfWords

Cross-Platform SIP & WebRTC Softphone App Build (iOS & Android) I’m a full-stack software engineer with expertise in React, Node.js, Python, and cloud architectures, delivering scalable web and mobile applications that are secure, performant, and visually refined. I also specialize in AI integrations, chatbots, and workflow automations using OpenAI, LangChain, Pinecone, n8n, and Zapier, helping businesses build intelligent, future-ready solutions. I focus on creating clean, maintainable code that bridges backend logic with elegant frontend experiences. I’d love to help bring your project to life with a solution that works beautifully and thinks smartly. To review my samples and achievements, please visit:https://www.freelancer.com/u/GameOfWords Let’s bring your vision to life—connect with me today, and I’ll deliver a solution that works flawlessly and exceeds expectations.

@amir672

I'm Amir, a seasoned Full-Stack Developer with a strong focus on mobile applications and web solutions. I have wide-ranging expertise that intersects perfectly with your project. As a proficient Flutter developer, I can build high-performance apps for iOS and Android - using React Native/Flutter if you prefer. I'm not only well-versed in these languages but can also deliver clean, well-commented source code for future ease of maintenance. Moreover, having worked with SIP and WebRTC before, I understand the intricacies and complexities involved and am well-suited to tackle all aspects of your task. In addition to my frontend skills and experience, I am capable of building robust backend systems that support the API needed for your project. My familiarity with Laravel (PHP) and Node.js makes me adept at RESTful API development and I can ensure seamless integration between your application and the backend. Lastly, my approach is deeply rooted in quality assurance. Not only do I aim for efficient code but my meticulousness during testing should reassure you that every aspect of the app would be tried-and-true, meeting all specifications outlined. This extends to providing a comprehensive configuration guide that showcases flexibility allowing multiple SIP domains, stun/turn, push keys while incorporating brand assets.

@sasaprogramer21

I can deliver a production ready softphone for iOS and Android where SIP drives signaling and WebRTC handles media, with a clean corporate UI and reliable push for inbound calls and messages. I have built softphone style apps with SIP registration, WebRTC media, call transfer, DTMF, BLF, voicemail playback, and threaded messaging, and I can share redacted screenshots and small code excerpts that demonstrate SIP plus WebRTC flows. The hardest piece here is on device audio mixing for merged calls. I would implement native mixing using platform audio engines and a deterministic mixing graph, then connect it to the WebRTC audio pipeline for consistent levels and low latency. Alongside that I will deliver robust call state handling, quality stats surface area including MOS jitter and loss, and a configuration layer for SIP domains STUN TURN and push credentials. Deliverables include native iOS Swift UI and Android Kotlin Compose builds, complete source in your repo, configuration guide, and QA checklist aligned to your lab tests. I am ready to build this with you in a focused professional way and see it through to a confident live demo, what PBX are you using and do you require SIP TLS by default? Estimated time: 3 - 5 months

@abhishek060

Hi, I can build a production-ready SIP + WebRTC softphone with native or cross plate form support, including on-device audio mixing, conferencing, SMS, voicemail, and full PBX integration. You’ll get a polished, enterprise-grade app with push notifications, call stats, clean UI, and fully documented source code ready for lab testing and deployment. Lets discuss on chat. Regards Abhishek

@SJMDEVELOPER

Hello, After reviewing your scope again, I’d strongly suggest building this using .NET MAUI instead of separate native codebases. Here’s why MAUI makes strategic sense for this project: • Single shared codebase for iOS & Android • Native performance (compiled, not hybrid web wrapper) • Direct access to platform APIs (CallKit, ConnectionService, audio engines) • Easier long-term maintenance and feature expansion • Faster iteration without sacrificing control For your specific requirements: ✅ WebRTC handles media (native bindings) ✅ SIP signalling via PJSIP integration (UDP/TLS) ✅ On-device local audio mixing implemented through platform-native audio layers exposed to MAUI ✅ APNs (VoIP) + FCM push support ✅ MOS, jitter & packet-loss metrics surfaced in UI ✅ BLF, transfer, DTMF, hold/resume ✅ Visual voicemail + SMS conversation view ✅ Hosted/local contacts & call history ✅ Embedded web view for your webpage MAUI allows us to maintain a unified business logic layer (SIP handling, conferencing control, stats reporting) while still using native iOS and Android capabilities where needed — especially for the complex audio mixing layer. This reduces duplicated effort, improves stability, and speeds up long-term updates. If you're open to this architecture, let’s have a short technical call to review your PBX environment and confirm SIP stack compatibility before locking final scope. Please initiate a message here so we can move forward. Best regards, Manoj

@ssquare489

I am Sumit Joshi from Sacesta Technologies. I can build a production-ready iOS and Android softphone using SIP for signalling and WebRTC for media, with a clean corporate UI and reliable push for calls and SMS. I have a couple of key questions before we start • Which PBX are you testing against, and do you require TLS plus SRTP end to end? • For on-device audio mixing, do you need true multi-party local mix, or only merging two active calls? Why work with me: My name is Sumit. I build real-time communication products where call state, media, and uptime matter. I delivered FileChannels, a secure platform with chat, voice, and video, and I can share NDA-safe demos, screenshots, and code snippets that show SIP and WebRTC work. Approach • Native audio pipeline for local mixing, echo control, and device route changes • SIP registration, BLF, hold, transfer, DTMF, merge, and call quality stats in-app • Visual voicemail and two-way SMS conversations • APNs and FCM push for inbound calls and messages with retry and logging • Config guide for SIP domains, STUN or TURN, push keys, and branding Please message me on Freelancer and I will share examples and a clear plan for your Hosted PBX lab tests and live handset demo. Regards, Sumit Joshi

@markupdudes

Hi, I have carefully reviewed your need for a cross-platform SIP & WebRTC softphone app for both iOS and Android that authentically integrates with your existing PBX and maintains a sleek, corporate design. With several years of experience in VoIP, mobile app development (iOS using SwiftUI and Android with Jetpack Compose), and building apps utilizing both SIP and WebRTC, I’m confident in delivering a production-ready solution tailored to your specifications. I have developed softphone applications featuring local audio mixing on-device, conferencing, BLF, call transfer, voicemail playback, two-way SMS, and comprehensive call quality stats. My approach will include native modules for local audio mixing, ensuring efficient performance and seamless user experience. I will provide clean UI consistent with your brand and detailed documentation for configuration and QA. I propose a 45-day timeline to deliver fully tested native builds and complete source code with a smooth onboarding QA process and support for live demo preparation. I’m excited to discuss how to best tailor the UI and integration. Can you share any existing design guidelines or branding assets that the new app should adhere to? Best regards,