  VLBI plays a unique and fundamental role in the maintenance of global
reference frames which are required for precise positioning in many research
areas related e.g to the understanding and monitoring of global changes, to
geodesy, to space missions etc. The International VLBI Service for Geodesy and
Astrometry coordinates internationally the VLBI components and resources and is
tasked by IAG and IAU for the provision of products describing the Celestial
Reference Frame through positions of quasars and their changes with time and
also for products describing the rotation of the Earth in space. This paper
summarises today's status of the products, achieved over the last years by
evolving the observing programs. It points out the activities to improve
further on the product quality to meet future service requirements, which will
come up with the need for highly precise global reference frames.
