  The production of strange mesons in collisions of Ar+KCl at a kinetic beam
energy of 1.756 AGeV is studied within a transport model of
Boltzmann-\"Uhling-Uhlenbeck (BUU) type. In particular, $\phi, K^+$ and $K^-$
yields and spectra are compared to the data mesured recently by the HADES
collaboration and the $\phi$ yield measured previously by the FOPI
collaboration. Our results are in agreement with these data thus presenting an
interpretation of the subleading role of $\phi$ decays into $K^-$'s and
confirming the importance of the strangeness-exchange channels for $K^-$
production.
