  We employ a dispersion relation that allows to recover the phase of the
electromagnetic form factor of the pion from its absolute value above
threshold. Compared to alternative approaches building on the phase, this
approach builds on experimental input directly accessible at colliders.
Employing the precise datasets from the $e^+e^-\to\pi^+\pi^-$ reaction, we
obtain the phase of the electromagnetic form factor up to $2.5$~GeV, well
beyond standard dispersive approaches. In addition, we separate the isovector
and isoscalar components, that allows to extract the $P$-wave $\pi\pi$ phase
shift. We also provide relevant results, including the radius of the form
factor and bounds in the spacelike region. Last, but not least, the study
assess potential systematic uncertainties from the interpolation method and
potential zeros of the form factor.
