  A two-dimensional, time-dependent numerical model is used to calculate the
modulation of cosmic rays in the heliosphere. Computations are compared to
spacecraft observations in the inner and outer heliosphere. It is shown that
the model produces cosmic ray proton intensities compatible to different
spacecraft observations on a global scale, at Earth and along both Voyager
spacecraft trajectories. The study reveals that when the same modulation
parameters, which resulted in compatible intensities along Voyager 1, were
assumed along the Voyager 2 trajectory, the model failed to reproduce the
observations. The study also found that any change in diffusion parameters
alone could not reproduce the cosmic ray observations along Voyager 2 so that
changes to the heliospheric geometry were necessary i.e the computed
intensities along both Voyager trajectories suggest that the heliosphere is
asymmetric. Furthermore, $E >$ 70 MeV and 133-242 MeV proton intensities along
Voyager 1 and 2 trajectories are predicted from end of 2012 onwards. It is
shown that the computed intensities along Voyager 1 increase with an almost
constant rate up to the heliopause. However, the model shows that Voyager 2 is
still under the influence of temporal solar activity changes because of its
relatively large distance to the heliopause. Along the Voyager 2 trajectory,
the intensities remained generally constant for some time and should soon start
to increase steadily.
