The Dial Tone Under 250,000 Clinicians
Mobile Heartbeat had the engineers to build its own voice stack, and decided a push engine that never drops a call was the wrong thing to build twice.
250,000+ monthly active clinicians on embedded voice that just rings, inside the Mobile Heartbeat platform.
Hospital communications were stuck in a stationary model long after the work stopped being stationary.
Nurses, physicians, and clinical staff move across floors every shift. But the voice infrastructure they were given was wired into desks, nurse stations, and overhead pages. Mobile Heartbeat had already closed most of that gap, clinical messaging, team coordination, broadcast alerts, all built for clinicians on the move. The missing layer was voice that worked on the same model: a peer to the platform, not a dialer bolted on top.
Mobile Heartbeat had the engineering team to build that voice layer themselves. That is exactly why they didn't. A push stack that rings every call on a locked, backgrounded, battery-throttled phone, across every iOS and Android power state, is not a weekend feature. It is a specialty product with its own decade of edge cases. You build one once to learn how hard it is. You don't build it twice.
And the stakes here are not customer-experience stakes. In a clinical setting, a missed call is not an inconvenience. It is a patient safety event.
The engineers to build voice themselves
and a decision that a push stack ringing every call was the wrong thing to build twice
250,000+ monthly active clinical users
on embedded Acrobits voice, running inside the Mobile Heartbeat platform
Voice became the dial tone under the platform
the layer nobody notices because it always rings; engineers went back to clinical features
Acrobits is invisible
to clinicians and hospital IT; Mobile Heartbeat owns the experience end-to-end
Mobile Heartbeat embedded Acrobits Cloud Softphone as its voice layer, white-labeled and invisible.
Today 250,000+ monthly active clinical users place and take calls inside the Mobile Heartbeat experience, with no separate dialer to download and no app to switch into. That number is the proof that matters, not because it is large, but because at that scale a push stack either rings every call or it becomes a standing clinical incident. It rings. Calls connect on backgrounded and battery-optimized devices, exactly where consumer-grade softphones go quiet.
The human turn is what the number bought. The 2 a.m. incident review, why did that call not ring, was a patient harmed, stopped being a recurring line item. Mobile Heartbeat's engineers stopped maintaining telephony plumbing and went back to building clinical workflows, the thing hospitals actually pay them for.
If you had to teach a platform team the one idea here, what is it?
The spec is public. The engine is not.
Anyone can read how push notifications are supposed to work, that spec is open to everyone. What almost nobody can do is run the accountable, maintained push engine that keeps ringing after Apple and Google change the rules again next quarter.
Mobile Heartbeat took the engine, not the recipe. That is the difference between open source and an open framework: somebody else owns the hard part, and stays on the hook for it.
See it running under your brand.
30 minutes. Branded build, billing model, and a store-listing plan walked through end-to-end.
How they used Acrobits
White-labeled Cloud Softphone, embedded in the platform. Clinicians see Mobile Heartbeat's brand, UI, and workflow. Acrobits carries the hard part underneath, out of sight, where the clinical user never has to think about it.
A foundation built for the use case. SIPIS local push delivers calls reliably to backgrounded and battery-optimized devices, landing them on the phone's own native call screen.
An encryption stack hospital IT can audit. TLS for signaling, SRTP for media, ZRTP end-to-end. Acrobits keeps the dial tone alive; Mobile Heartbeat builds the clinical product on top of it. Neither side does the other's job.
What they needed
- Voice that survived locked screens, backgrounded apps, and battery-aggressive Androids at clinical-grade reliability: every call, every shift, every device
- A voice layer that behaved like a peer to messaging and coordination, not a separate dialer clinicians had to switch into
- An embedded SDK they could compose into their own platform, not a stand-alone app they had to convince hospitals to deploy
- A maintained push engine that stays ringing after each iOS and Android change, the part they explicitly chose not to own
- An encryption stack hospital security teams could audit on their own terms: TLS, SRTP, ZRTP
Technical detail
Features that did the work
SIPIS local push
sub-half-second call delivery on backgrounded and battery-optimized devices, the dial tone that always rings.
Fully embedded SDK integration
the calling layer runs inside Mobile Heartbeat's platform; Acrobits is invisible to clinicians, hospital IT, and security auditors.
Encryption stack (TLS / SRTP / ZRTP)
auditable for hospital security teams on their own terms.
Active-user billing
scales with real usage, not provisioned headcount.
From our Trustpilot reviews
Another partner described the same quiet reliability once the app is in production.
“The mobile app has been very reliable and fulfills the needs of our customers. The ease to onboard has made it very simple to introduce this app into our service portfolio. The technical support is very timely and always spot on.”
The best clinical voice layer is the one nobody notices, the dial tone under the platform.
You build a push stack once to learn how hard it is. You don't build it twice.