I build, integrate, and debug VoIP and calling systems on Asterisk from a single SIP trunk to multi-tenant calling platforms.
Whatever the calling problem is setup, integration, broken audio, or a full build I take it to production and document it for your team.
What I help with:
→ Asterisk, Wazo, FreePBX, FusionPBX — setup, configuration, and production debugging
→ SIP trunking with any provider — Telnyx, Twilio, Plivo, Bandwidth
→ Inbound/outbound call routing, IVR, queues, CDRs, recordings, webhooks
→ Kamailio + RTPEngine — SIP routing and media bridging
→ WebRTC dialers & softphones — JsSIP, SIP.js, MicroSIP, Zoiper, Linphone
→ WhatsApp Business / Meta Calling — SIP gateway, DTLS-SRTP, ICE, RTP
→ NAT, codec, and one-way-audio troubleshooting on live SIP traces (sngrep, Wireshark)
→ Multi-tenant VoIP SaaS with REST API management
→ Voice AI & call-automation pipelines on top of SIP (LiveKit, agents)
→ Self-hosted on DigitalOcean, Azure, AWS — any Linux host
Recent proof: I built multi-tenant WhatsApp Business Calling on a Wazo/Asterisk platform — a Kamailio → RTPEngine → Asterisk media bridge handling DTLS-SRTP from Meta's SIP gateway, with a WebRTC dialer, per-tenant routing, IVR, recordings, CDRs, and full API control. The client kept me on for ongoing work. I've also deployed self-hosted Asterisk on DigitalOcean with full trunk and dial-plan config — production, not a test lab.
Tell me what you're building or what's broken, and I'll tell you straight if I'm the right fit.
— Zahid
MQTT
Linux
Server Administration
Firebase
Supabase
Asterisk
Kamailio
VoIP
WebRTC
FreePBX
VoIP PBX
Twilio API
IVR Software
Session Initiation Protocol
Linux System Administration
REST API
n8n
AI Agent Development
Network Administration
Telecommunications
Rehman A.
Lahore, Pakistan
$15/hr
5.0
10 jobs
Reman Ali is VOIP and IT Professional with more than 5 year+ of
in-depth knowledge & expertise in leading Cisco, Asterisk VoIP,
Freeswitch, Vicidial and FreePBX. Vast experienced in the support and development of
VOIP & telecommunications projects. Excellence communication
skills with highest level of customer support. Diverse expertise on
operating systems (Linux & Windows) and multiple CRMs.
VoIP
CentOS
Call Center Management
Business Process Outsourcing IT Services
FreePBX
API Integration
VICIDIAL
VoIP Administration
GSM
Asterisk
3CX
VoIP Software
Session Initiation Protocol
Abid Ur R.
Lahore, Pakistan
$45/hr
4.6
307 jobs
Hello, Thanks for visiting my profile. This is Abid Ur Rehman, a certified Asterisk Developer DCAP, VoIP Consultant, VICIDial, FreePBX SCE, 3CX v18 and v20 Certified Advanced Engineer, Elastix ECE, GoAutoDial, The SIP School SSCA, PBXWare, A2Billing, FreeSWITCH, Twilio, FusionPBX, ASTPP, Network CCNA, Windows Servers MCSE, and Linux RHCE certified expert.
I graduated with a BS in Telecommunication and an MSc in Telecommunication Networks.
Having over 13 years of VoIP/Linux/IT/network planning, design, development, deployment, optimization, administration, and support experience in top-notch organizations such as Telappliant Ltd., Cybergen, SCB Global, Dialer360, and Astericom.
Skills and Certification:
IP PBX: 3CX, Asterisk, FreePBX, Elastix, PBXware MT, FreeSWITCH, FusionPBX, Issabel, VoIPOffice
AI Agents/Integration: ElevenLabs, Vapi
SMS Blast/Broadcast using SignalWire, VoIP.ms, Telnyx, Anveo, Bandwidth, Plivo, Skyetel, Twilio, VoxTelesys, BulkSolutions, Flowroute, Intelepeer, and BulkVS
Telecom Billing: A2Billing, ASTPP, VOS3000, and Magnus Billing.
Dialer: VoiceBroadcast, VICIDial, GoAutoDial, VICIBox Multi-Server Clustering, Dialer360, Primo Dialer
IP Phones: Aastra, AND phone, Algo, AudioCodes, Cisco, Cisco/Linksys, CloudTC, Cortelco, CyberData, Digium, H-Tek, Incom, Intelbras, Konftel, Mocet, Norphonic, Obihai, Panasonic, Patton, Phoenix Audio, Polycom, Snom, Thomson, Unidata, Uniden, VTech, Xorcom, Yealink, Yealink/Dreamwave
IP PBX (hardware): Sangoma PBXact UC / FreePBX, Elastix IP PBX, Grandstream UCM, Yeaster S-series, Renegadepbx-1U-Appliance-with-FreePBX, Patton's gateways
VoIP Providers:
USA and Canada: Astericom, Twilio, VoIPdotms, Switch2VOIP, SignalWire, Anveo, Alcazarnetwork, voxbeam, Telus, RingCentral, Call Centric, Voyant (Vitelity), Nextiva, bandwidth, Altotelecom, FlowRoute, QuestBlue, sipdotus, DIDLogic, Nexmo, Plivo, siptrunkdotcom, Telnyx, IDTExpress, Zadarna
SMS and Bulk SMS: I can write code for you to send and receive SMS using any Asterisk and FreeSWITCH server and through popular providers like Telnyx, Twilio, Bandwidth, VoIPdotms, and SignalWire. For bulk SMS, I can set up a code with the front end for sending bulk SMS from a CSV .
UK: Fuse 2, BT, VoIPTalk, DrayTEL, Telappliant, Gamma, sipgate, VoIPFone, VoiceFlex, Voicehost, Brightstar, Yellowgrid, Gradwell, T4com Ltd, Voxbeam, and Spitfire
Linux Distros: CentOS, Redhat EL, Ubuntu, OpenSUSE, Debian, Back Track (Kali Linux)
Windows machines: Windows Server 2012 and 2016, Windows Desktop 11, 10, 8, 7, and XP.
Cloud Platforms: AWS EC2 and LightSail, GCP, Vultr, BlueHost, HostGear, Hetzner, and Digital Ocean
Coding: PHP, MySQL, Lua, XML, JSON, HTML
I would be very happy to assist start-ups as well as SMEs in achieving their goals and business objectives.
Thank you!!
VoIP
VICIDIAL
FreePBX
Linux System Administration
Asterisk
3CX
MySQL
VoIP PBX
Full-Stack Development
VoIP Administration
Twilio
PHP
VoIP Software
PBX
AI Bot
Ahsan U.
Lahore, Pakistan
$30/hr
5.0
24 jobs
I am a VoIP and network security expert with over 7 years of hands-on experience delivering custom communication solutions for businesses worldwide.
I specialize in deploying and supporting VoIP systems such as Avaya, Asterisk, 3CX, Mitel, FreePBX, FusionPBX and Kamailio, with deep expertise in SIP routing, SIP trunking, and cloud telephony. I’ve worked with major providers including Twilio, Voip.ms, Telnyx, and Voxtelesys, and offer reliable integration and troubleshooting services.
I also have a strong background in VPNs, firewalls, and secure networking — including Fortinet, pfSense, OPNsense, WireGuard, OpenVPN, and IPSec setups — especially for remote access and restricted regions.
Additionally, I offer AI Voice Assistant setup and integration with VoIP systems, as well as AI chatbots for websites and WhatsApp Business automation.
My clients benefit from project-based deployment, long-term support, and a live lab environment where I demo solutions in real time before final delivery and deliver reliable, well-tested solutions designed around your business needs.
Let’s work together to secure and optimize your communications systems.
Avaya
Asterisk
3CX
FreePBX
PBX
Call Center Software
PfSense
Firewall
FortiGate Firewall
OpenWrt
Muhammad Sohaib K.
Karachi, Pakistan
$15/hr
5.0
13 jobs
CAREER OBJECTIVES:
To perform and grow in a challenging environment with many opportunities to learn
and grow both in experience and as a person
Ansible
Amazon Web Services
Linux
Docker
Linux System Administration
VoIP Software
VoIP
VPN
VoIP Administration
Khubaib A.
Lahore, Pakistan
$35/hr
5.0
33 jobs
𝗔𝗜/𝗠𝗟 𝗘𝗻𝗴𝗶𝗻𝗲𝗲𝗿 | 𝗦𝗶𝗴𝗻𝗮𝗹 𝗣𝗿𝗼𝗰𝗲𝘀𝘀𝗶𝗻𝗴 𝗔𝗹𝗴𝗼𝗿𝗶𝘁𝗵𝗺𝘀 | 𝗥𝗲𝗮𝗹-𝗧𝗶𝗺𝗲 𝗦𝘆𝘀𝘁𝗲𝗺𝘀 | 𝗩𝗼𝗶𝗰𝗲 𝗔𝗜 & 𝗖𝗼𝗻𝘃𝗲𝗿𝘀𝗮𝘁𝗶𝗼𝗻𝗮𝗹 𝗔𝗜 𝗲𝗻𝗴𝗶𝗻𝗲𝗲𝗿 (𝗦𝗧𝗧/𝗧𝗧𝗦 + 𝗿𝗲𝗮𝗹-𝘁𝗶𝗺𝗲 𝗮𝗴𝗲𝗻𝘁𝘀) | 𝗪𝗲𝗯𝗥𝗧𝗖/𝗟𝗶𝘃𝗲𝗞𝗶𝘁 | 𝗦𝗜𝗣/𝗩𝗼𝗜𝗣 (𝗧𝘄𝗶𝗹𝗶𝗼/𝗔𝘀𝘁𝗲𝗿𝗶𝘀𝗸)
I build 𝘃𝗼𝗶𝗰𝗲 𝗮𝗴𝗲𝗻𝘁𝘀 and 𝗹𝗼𝘄-𝗹𝗮𝘁𝗲𝗻𝗰𝘆 𝗮𝘂𝗱𝗶𝗼/𝘃𝗶𝗱𝗲𝗼 𝘀𝘆𝘀𝘁𝗲𝗺𝘀 that actually hold up on real calls, in production, under load. If you're fighting latency, 𝗰𝗮𝗹𝗹 𝗱𝗿𝗼𝗽𝘀, 𝗡𝗔𝗧/𝗧𝗨𝗥𝗡 𝗶𝘀𝘀𝘂𝗲𝘀, 𝗿𝗼𝗯𝗼𝘁𝗶𝗰 𝘁𝘂𝗿𝗻-𝘁𝗮𝗸𝗶𝗻𝗴, 𝗿𝗲𝗰𝗼𝗿𝗱𝗶𝗻𝗴 𝗳𝗮𝗶𝗹𝘂𝗿𝗲𝘀 or a 𝘃𝗼𝗶𝗰𝗲 𝗮𝗴𝗲𝗻𝘁 that breaks the moment a real customer interrupts it, I can take it end-to-end and ship something stable. I focus on what client's measure, response latency, barge-in handling, RTT, jitter, packet loss, concurrency and cost per call.
𝗧𝗲𝗰𝗵𝗻𝗶𝗰𝗮𝗹 𝘀𝘁𝗿𝗲𝗻𝗴𝘁𝗵𝘀 𝗶𝗻𝗰𝗹𝘂𝗱𝗲:
Python, NumPy, SciPy, Pandas, Scikit-learn
ML model development + evaluation
Audio/signal processing pipelines
Feature engineering + algorithm optimization
Distributed computing concepts
Real-time data handling & automation
𝗪𝗵𝗮𝘁 𝗜 𝗯𝗿𝗶𝗻𝗴 𝘁𝗼 𝗲𝗻𝗴𝗶𝗻𝗲𝗲𝗿𝗶𝗻𝗴 𝘁𝗲𝗮𝗺𝘀:
Research-backed algorithm design
Strong mathematical and analytical foundation
Production-aware AI/ML integration
System-level thinking (latency, throughput, scalability)
Clear documentation and reproducible workflows
𝗖𝗼𝗿𝗲 𝗖𝗮𝗽𝗮𝗯𝗶𝗹𝗶𝘁𝗶𝗲𝘀:
WebRTC / LiveKit Engineering
SFU scaling strategies, TURN/STUN configuration, ICE tuning
Optimizing jitter, packet loss, simulcast/SVC, bitrate adaptation
Debugging join failures, audio/video inconsistencies, device issues
𝗠𝗲𝗱𝗶𝗮 𝗣𝗶𝗽𝗲𝗹𝗶𝗻𝗲𝘀:
FFmpeg and OBS workflows for ingest → process → record → distribute
Reliable multi-track recording and egress configurations
Low-latency transcoding and optimized CPU/GPU usage
𝗜𝗻𝘁𝗲𝗿𝗮𝗰𝘁𝗶𝘃𝗲 & 𝟯𝗗 𝗦𝘁𝗿𝗲𝗮𝗺𝗶𝗻𝗴:
Unity, Unreal and Omniverse real-time streaming setups
Digital twin + avatar pipelines with synchronized audio/video
Ultra-low-latency input → render → stream loops
𝗔𝗜/𝗠𝗟 & 𝗖𝗼𝗺𝗽𝘂𝘁𝗲𝗿 𝗩𝗶𝘀𝗶𝗼𝗻:
Real-time OCR, text extraction, scene understanding
Background removal, segmentation, enhancement
Avatar/lip-sync triggers, real-time CV analytics
ML inference integrated into WebRTC with strict latency control
𝗗𝗲𝘃𝗢𝗽𝘀 & 𝗢𝗯𝘀𝗲𝗿𝘃𝗮𝗯𝗶𝗹𝗶𝘁𝘆:
Dockerized deployments, environment separation
Monitoring (jitter, RTT, CPU/mem, packet loss, TURN usage)
Alerting, runbooks, load testing, failure-mode analysis
𝗖𝗼𝗿𝗲 𝗖𝗮𝗽𝗮𝗯𝗶𝗹𝗶𝘁𝗶𝗲𝘀:
WebRTC / LiveKit Engineering
Media Pipelines
Interactive & 3D Streaming
AI/ML & Computer Vision
DevOps & Observability
𝗠𝘆 𝗺𝗶𝘀𝘀𝗶𝗼𝗻:
To create next-generation communication systems by merging AI/ML, signal processing and automation and to invent efficient algorithmic approaches that solve complex real-world challenges.
Need a solid solution? Drop a text anytime
Machine Learning
Audio Engineering
Python
AI Agent Development
LLM Prompt Engineering
WebRTC
Twilio API
Node.js
React
Computer Vision
Natural Language Processing
Artificial Intelligence
API Development
Web Development
Machine Learning Model
Deep Learning
TensorFlow
ML Automation
Next.js
Full-Stack Development
How it works
Post a job for freePost a job
Tell us what you need. Create your own job post or generate one with AI then filter talent matches.
Hire top talent fast
Consult, interview, and hire quickly, so you can meet the freelancers you're excited about.
Collaborate easily
Use Upwork to chat or video call, share files, and track project progress right from the app.
Payment simplified
Manage payments in one place with flexible billing options. Only pay for approved work, hourly or by milestone.
Don't just take our word for it
“Upwork provides an umbrella-level of security. I can see a talent’s work history and ratings. I can hold payments in escrow. I can communicate through Upwork Messages instead of working through my email address.”
KD
Kim Darling
Emerald Tiger
“Upwork is the best platform to hire skilled professionals when we're not looking for a full-time employee. All the companies in our portfolio use Upwork to find talent across a wide range of fields.”
DM
David Merry
Kinetic Investments
“Our very specific requirements can be a challenge—With Upwork, we’re able to access a bigger community to ensure the success of our projects.”
KK
Katja Krohn
Summa Linguae
How do I hire a Freeswitch Specialist in Pakistan on Upwork?
You can hire a Freeswitch Specialist in Pakistan on Upwork in four simple steps:
Create a job post tailored to your Freeswitch Specialist project scope. We'll walk you through the process step by step.
Browse top Freeswitch Specialist talent on Upwork and invite them to your project.
Once the proposals start flowing in, create a shortlist of top Freeswitch Specialist profiles and interview.
Hire the right Freeswitch Specialist for your project from Upwork, the world's largest work marketplace.
At Upwork, we believe talent staffing should be easy.
How much does it cost to hire a Freeswitch Specialist?
Rates charged by Freeswitch Specialists on Upwork can vary with a number of factors including experience, location, and market conditions. See hourly rates for in-demand skills on Upwork.
Why hire a Freeswitch Specialist in Pakistan on Upwork?
As the world's work marketplace, we connect highly-skilled freelance Freeswitch Specialists and businesses and help them build trusted, long-term relationships so they can achieve more together. Let us help you build the dream Freeswitch Specialist team you need to succeed.
Can I hire a Freeswitch Specialist in Pakistan within 24 hours on Upwork?
Depending on availability and the quality of your job post, it's entirely possible to sign up for Upwork and receive Freeswitch Specialist proposals within 24 hours of posting a job description.