sentences:  The system was built up in West Germany and West Berlin, but following German reunification in 1990, was rapidly built up in the new German states.By December 1988, the service had grown to nearly 100,000 customers, and reached a peak user base of around 800,000 in the early 1990s.It remained popular throughout the decade as a preferred system for mobile car phones, particularly rural taxi services, where it enjoyed an advantage in reception.