A methodology of quantum dynamics based on interacting trajectories without reference to any wave function is applied to ultrashort laser ionization of a model hydrogen atom. The pulses are chosen to be so short that the relative phase between the carrier wave and the pulse envelope becomes important As main results we show that the trajectory-only approach is capable of correctly describing the large amplitude motion and energetics of the laser driven electron and of reproducing carrier-envelope effects onto the photoelectron spectra. It also provides an intuitive picture of the dynamical quantum processes involved.