  Magneto-optical parameters of trions in novel large and symmetric InP-based
quantum dots, uncommon for molecular beam epitaxy grown nanostructures, with
emission in the third telecom window, are measured in Voigt and Faraday
configurations of external magnetic field. The diamagnetic coefficients are
found to be in the range of 1.5-4 {\mu}eV/{\T^2}, and 8-15 {\mu}eV/{\T^2},
respectively out of plane and in plane of the dots. The determined values of
diamagnetic shifts are related to the anisotropy of dot sizes. Trion g-factors
are measured to be relatively small, in the range of 0.3-0.7 and 0.5-1.3, in
both configurations respectively. Analysis of single carrier g-factors, based
on the formalism of spin-correlated orbital currents, leads to the similar
values for hole and electron of {\sim} 0.25 for Voigt and {\g_e} {\approx} -5;
{\g_h} {\approx} +6 for Faraday configuration of magnetic field. Values of
g-factors close to zero measured in Voigt configuration make the investigated
dots promising for electrical tuning of g-factor sign, required for schemes of
single spin control in qubit applications.
