(Reuters) - AT&T Inc missed fourth-quarter revenue estimates on Wednesday as another decline in subscriptions to satellite TV provider DirecTV overshadowed an increase in monthly phone customers.AT&T has spent a combined $134 billion (£103 billion) on DirecTV and Time Warner to transform itself into a media company, but is struggling to stem the loss of valuable satellite subscribers as audiences switch to streaming services. Analysts at New Street Research said in a note that although AT&T's..