1.  subscriber(n = noun.person) endorser, indorser, ratifier - someone who expresses strong approval;
is a kind of admirer, booster, champion, friend, protagonist, supporter
Derived form verb subscribe₃

2.  subscriber(n = noun.person) reader - someone who contracts to receive and pay for a service or a certain number of issues of a publication;
is a kind of client, customer
Derived form verb subscribe₅

3.  subscriber(n = noun.person) contributor - someone who contributes (or promises to contribute) a sum of money;
is a kind of bestower, conferrer, donor, giver, presenter
Derived form verb subscribe₄

1.  One who subscribes; one who contributes to an undertaking by subscribing. [1913 Webster]

2.  One who enters his name for a paper, book, map, or the like. Dryden. [1913 Webster]

subscriber, n.
1 a person who subscribes.
2 a person paying for the hire of a telephone line.

Idiom:
subscriber trunk dialling Brit. the automatic connection of trunk calls by dialling without the assistance of an operator.

digital subscriber line, subscriber line