Credit: what were the problems?

Two new digital telecommunications methods used for verification of credit cards by retail establishments are examined. Digital Data Voice Over (DDOV) and Integrated Services Digital Network (ISDN), which both reduce response time to four to five seconds, are not being widely accepted by stores because the services are not easily available and are expensive to implement. The popularity and rapid growth of the dial-up service, Feature Group B, also known 950 service, which requires 10-12 seconds to get a response, has also hampered the growth of DDOV and ISDN.