"El telÄfono estç en una lista negra" means that the user has reached the limit for retrying the connection. The maximum number for redialing the same phone number is four. This number is set by the customer's Spanish phone company, and once you have exceeded this number you get the error "this phone number is black listed". You must wait a certain amount of time before trying again.
This code is not often used in Spain; it is more prevalent in other European countries.
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