<P> At the end of RCC's existence, industry associations were working on a technical standard that would have allowed roaming, and some mobile users had multiple decoders to enable operation with more than one of the common signaling formats (600 / 1500, 2805, and Reach). Manual operation was often a fallback for RCC roamers . </P> <P> In 1969 Penn Central Railroad equipped commuter trains along the 360 kilometres (220 mi) New York - Washington route with special pay phones that allowed passengers to place telephone calls while the train was moving . The system re-used six frequencies in the 450 MHz band in nine sites . </P> <P> In the UK, Channel Islands and elsewhere the "Rabbit" phone system was briefly used, being a hybrid of "cell" base stations and handsets . One major limitation was that you had to be less than 300 feet (closer with buildings) from a base due to power limitations on a portable device . With modern technology a similar variant is being considered for Apple's new 4G "smart watch" so they can be used in large events in a broadly similar way to a femtocell . </P> <Table> <Tr> <Td> </Td> <Td> This section needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (April 2012) (Learn how and when to remove this template message) </Td> </Tr> </Table>

When was the first cell phone invented timeline