Your extension on Windows and Android

OneCall is TMO's own softphone, in the spirit of MicroSIP. The Windows desktop app and the Android app share one phone engine, so they behave the same everywhere. Staff can take their office extension home, on the road, or to a hot desk, without a desk phone.

🪟 Windows desktop🤖 Android🍎 iOS-ready

How it connects

OneCall registers over secure WebSocket (WSS) to OnePBX, OneBox or any WebRTC-ready PBX.
It uses the same audio engine as Chrome, which brings Opus, echo cancellation and NAT traversal.
For providers that only offer UDP 5060, a TMO SBC or PBX sits in between as the gateway.

Up to 8 linesEach account registers on its own with a status light, like a desk phone.
Line choicePick the outgoing line or set a default. Incoming calls show which line is ringing.
Call controlMute, hold/resume, blind transfer, DTMF, and multiple calls with auto-hold.
Per-account audioReorder codecs (Opus, G.722, G.711) and choose the DTMF method.
Audio qualityEcho cancellation, noise suppression, automatic gain, and device choice.
History & contactsDialpad, call history with a missed-call badge, and contact search.
ProductivityAuto-answer, Do Not Disturb, dial prefix and five ringtones.
ResilientRe-registers automatically with backoff after network loss.
Windows extrasTray status, start with Windows, click-to-call sip:/tel: links, notifications.
Android extrasSystem ringtone, earpiece/speaker toggle, proximity sensor and haptics.

Technical data

SIP stack: SIP.js (shared TypeScript core)
Windows: Electron + React
Android / iOS: Expo + react-native-webrtc
Codecs: Opus, G.722, G.711 µ-law / A-law
DTMF: RFC 2833, SIP INFO fallback
Transport: SIP over secure WebSocket (WSS)

See OneCall working on a live system

We'll walk you through it on our servers, set up for the way your business works.

Request a demo Call +254 734 573 283 WhatsApp us

The platform

Works with the rest of the TMO family

◆OneCoreCarrier softswitch with LCR and real-time prepaid billing ⬢OneSBCCarrier-grade session border controller with transcoding ▣MiniSBCCompact SBC for single sites and interconnects ☎OnePBXBusiness phone system with visual IVR and AI receptionist ◉OneBoxContact-centre suite with speech IVR and data lookups ♪TTS AutodialerPersonalised text-to-speech voice campaigns