  This paper presents the first detection of Shapiro delay from the binary
millisecond pulsar PSR J1811-2405. We report a 11-${\sigma}$ measurement of the
orthometric amplitude, h$_3$=6.8(6)x10$^{-7}$, and a 16-${\sigma}$ measurement
of the orthometric ratio, ${\varsigma}$= 0.81(5). Given the relatively high
orbital inclination, i= 79(2) deg, of this binary system, we obtain constraints
on the companion mass of m$_c$= 0.31$\substack{+0.08 \\ -0.06}M_\odot$. The
pulsar mass is currently less well constrained, with a value of
2.0$\substack{+0.8 \\ -0.5}M_\odot$. The companion mass and the orbital period
are in agreement with the prediction made by previous numerical calculations of
the evolution of compact binary systems. From a study of the polarization, we
find that the orbital inclination angle is ~100 deg and that PSR J1811-2405 is
an orthogonal rotator. In addition, the ${\mu}$s-level timing precision
together with its narrow profile make PSR J1811-2405 a good candidate for
inclusion in the pulsar timing arrays being used to detect nHz Gravitational
waves.
