Feel the serve before you see it.
TELLSOLE uses machine vision to read your opponent's service motion through a camera or your phone. The insoles pulse under your left or right foot before the racket meets the ball.
The first production run is sold out. The next delivery goes to the waitlist first.
A serve gives you half a second. Your eyes need most of it.
A 190 km/h first serve reaches you in about 560 ms. By the time you've seen where it's going, it's already bounced. TELLSOLE reads the motion instead of the ball, so the signal arrives before contact.
A 650 ms head start. That's the gap between feeling the serve and seeing it.
Nobody on the other side of the net will know you're training.
The insole sits under your own. It has no lights, makes no sound and needs no screen on court: the phone does its work from the fence or the stands.
You're drilling your reflexes against real serves. From across the net, you just look like a player who reads serves unusually well.
How it works
- 1
Capture
Set one phone behind the baseline, facing the server. For higher accuracy, add a second one beside the court, level with the net, for a side view. The Pro Cam does the same job on its own tripod.
- 2
Learn
Load your opponent's matches: broadcast clips or your own recordings. A machine vision model learns their tells: where the ball is tossed, how far the shoulders turn, the angle of the back foot, the moment the wrist drops. Every server has them. Almost nobody can read them in real time.
- Toss drifts 12 cm right: slice wide
- Shoulders turn past the baseline: kick to the body
- Back foot opens early: flat down the T
- 3
Feel
During the point, machine vision tracks the service motion frame by frame and the insoles pulse under your left foot, your right foot, or both, well before the racket meets the ball.
Three signals. Nothing to learn.
The pulse comes from the side the ball is going to, so your body reacts before you've thought about it.
91.32%of serves called in the right direction in testing
Left pulse
The serve is going to your left.
Right pulse
The serve is going to your right.
Both pulse
The serve is coming at your body.
Choose your setup
Every setup is sold out. Tap Notify me and we'll email you before the next delivery opens.
Sold out
Phone Solo
€389
The phone app, a licence and the insoles. The fastest way to start.
- TELLSOLE app for iPhone and Android
- Licence for 1 smartphone
- 1 pair of TELLSOLE insoles
Sold out
Phone Duo
€520
Two phones, two angles, higher accuracy. Courtside or up in the stands.
- TELLSOLE app for iPhone and Android
- Licence for 2 smartphones
- 1 pair of TELLSOLE insoles
- Higher accuracy: the model reads each serve from two angles
Sold out
Pro Cam
€1,800
Most chosen by coaches
A dedicated vision camera with on-board processing. No phone needed on court.
- 1 pair of TELLSOLE insoles
- TELLSOLE Vision camera with edge processor
- Carbon tripod
- 2 years of model updates
Sold out
Academy
€4,600
For clubs and coaches running several players on one court.
- 4 pairs of TELLSOLE insoles
- 2 TELLSOLE Vision cameras
- Coach dashboard
Replacement insoles
€149 per pair
Sold out
Insoles wear out; your app, licence and camera don’t. Swap in a fresh pair and keep training. Works with every setup.
Already on court
Players train with TELLSOLE every day. Most of them would rather you didn't know.
“After two weeks I stopped guessing on the ad side. My opponents think I've just got better at reading serves.”
“We load the opponent's recent matches the night before and drill returns against their serve in the morning. By the afternoon, the reads are in the player's feet.”
“You forget it's there. Then it buzzes and your feet are already moving.”
Questions
Can I use TELLSOLE in a tournament?
TELLSOLE is built for training. ITF rules and most tournament regulations don't allow devices that give a player information during a match. Check the rules of every event you play.
Can anyone see or hear it?
No. It sits under your own insole, has no lights and vibrates silently. Only you feel it.
Where do the cameras go?
One phone on the fence behind the baseline is enough to start. A second phone at the side or in the stands improves accuracy. The Pro Cam stands on its own tripod and needs no phone at all.
How accurate is it?
In our test sessions TELLSOLE called the direction of 91.32% of serves correctly. Accuracy grows with more footage of the opponent, and a second phone (Phone Duo), the dedicated Pro Cam or Academy’s two cameras all do better than a single phone.
How much footage does it need?
About 200 serves from one opponent give a reliable model. With 1,000 or more it starts to pick up how they serve under pressure, on break points and second serves.
How fast is it?
From the start of the service motion to the pulse takes under 120 ms on a recent phone or the Pro Cam. On average the pulse arrives 350 ms before racket contact.
Battery and sizes?
Up to 9 hours of play per charge, with USB-C charging through the heel pod. Trim-to-fit insoles in EU sizes 36–48.
What if the insoles wear out?
With regular play a pair lasts around six months. Replacement insoles cost €149 per pair and pair with the app, licence and cameras you already have.
What happens to the video?
Footage is processed on your phone or the Pro Cam. Only the trained model is kept, not the video, unless you choose to save it.
When is the next delivery?
We don't announce dates. Everyone on the waitlist hears first and gets 48 hours to order before anyone else.
Sold out. Be first for the next delivery.
Leave your email. When the next delivery is ready, the waitlist gets 48 hours to order before anyone else.