BitsPath
Carrier-grade CPaaS with a pure Rust PBX core and a .NET service set covering SMS, email, WhatsApp, and voice on a unified API.
Definition
What is the BitsPath case study?
BitsPath is a LoneSock-built communications platform with a pure Rust PBX core and a .NET service set on top. It covers voice (SIP, RTP, SRTP, WebRTC), SMS routing across operators, email delivery, and WhatsApp Business through a single API surface, and is now operated as a KaritKarma platform product.
The Challenge
What we were solving for.
Building a CPaaS to compete with the global incumbents requires carrier-grade voice from day one. Existing open-source PBX stacks carry legacy assumptions that make latency, concurrency, and observability hard to control.
The platform had to cover voice (SIP, RTP, SRTP, WebRTC), SMS across multiple operators, email delivery with strong inbox placement, and WhatsApp Business through a single API surface that did not force the caller to learn each channel's quirks.
Local SMS delivery in Bangladesh benefits from direct-operator interconnect over SIGTRAN/SS7. There was no off-the-shelf library in a language suitable for high-concurrency, low-latency processing in the region.
What We Built
Technical architecture.
A pure Rust PBX engine for the real-time path. Rust was chosen for predictable latency and memory safety. The PBX handles SIP registration, call routing, RTP and SRTP media, and the WebRTC gateway.
A .NET service set around the PBX covering SMS routing with operator-aware selection, email delivery with proper DKIM and SPF and DMARC hygiene, WhatsApp Business, campaigns, and CRM-style contact handling.
A unified REST API across all channels so a caller can send an SMS, place a call, queue an email, or fire a WhatsApp message through the same authentication and idempotency model.
A SIGTRAN/SS7 SMS gateway enabling direct-operator interconnect, removing an aggregator hop on local routes.
Key Numbers
Attributed, honest figures.
We publish numbers that the engagement supports. Unverifiable marketing metrics are not on this page.
Technology Stack
What we built it with.
Outcome
What the engagement delivered.
The platform delivers carrier-grade voice with predictable resource consumption under concurrency thanks to the Rust core.
Email delivery runs with high inbox placement through proper DKIM, SPF, and DMARC configuration combined with IP warming and content hygiene.
Direct SIGTRAN/SS7 interconnect reduces cost and latency on local SMS routes compared with aggregator-only delivery.
Questions
FAQ for the BitsPath engagement.
What did LoneSock build for BitsPath?
LoneSock built the full BitsPath platform: the Rust PBX core, the .NET service set, the unified REST API, and the SIGTRAN/SS7 SMS gateway. It is now operated as a KaritKarma platform product.
What tech stack was used?
Rust for the real-time PBX core. .NET 10 for the service set around it. SIP, RTP, SRTP, and WebRTC for voice transport. PostgreSQL for state. Docker for deployment.
Why a pure Rust PBX rather than Asterisk or FreeSWITCH?
Rust gives predictable latency, predictable memory behaviour, and a clean concurrency model. Existing open-source PBX stacks carry legacy assumptions that make those guarantees difficult to enforce at carrier-grade scale.
Is the platform still maintained?
Yes. BitsPath is an active KaritKarma platform product with ongoing development. LoneSock continues to deliver new capabilities into it.
Can LoneSock integrate BitsPath into our product?
Yes. The unified API is designed for that. LoneSock can also build a thin product adapter so the BitsPath channels map cleanly onto your existing notification and ordering flows.
Working on something similar
We have shipped this class of system before. Tell us what you are dealing with.
$20/hr time and materials, fixed-price milestones, or retainer. Source code is yours.