  We study the stability of single server retrial queues under general
distribution for retrial times and stationary ergodic service times, for three
main retrial policies studied in the literature: classical linear, constant and
control policies. The approach used is the renovating events approach to obtain
sufficient stability conditions by strong coupling convergence of the process
modeling the dynamics of the system to a unique stationary ergodic regime. We
also obtain instability conditions by convergence in distribution to improper
limiting sequences.
