To be clear, the full text of that portion of the legislation says:
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(a) In General- Section 2703 of title 18, United States Code, is amended by adding at the end the following:
`(h) Retention of Certain Records- A provider of an electronic communication service or remote computing service shall retain for a period of at least 18 months the temporarily assigned network addresses the service assigns to each account, unless that address is transmitted by radio communication (as defined in section 3 of the Communications Act of 1934).'.
(b) Sense of Congress- It is the sense of Congress that records retained pursuant to section 2703(h) of title 18, United States Code, should be stored securely to protect customer privacy and prevent against breaches of the records.
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In other words, it amends the existing language [0] which says (in part):
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A provider of electronic communication service or remote computing service shall disclose to a governmental entity the—
(A) name;
(B) address;
(C) local and long distance telephone connection records, or records of session times and durations;
(D) length of service (including start date) and types of service utilized;
(E) telephone or instrument number or other subscriber number or identity, including any temporarily assigned network address; and
(F) means and source of payment for such service (including any credit card or bank account number),
of a subscriber to or customer of such service when the governmental entity uses an administrative subpoena authorized by a Federal or State statute or a Federal or State grand jury or trial subpoena or any means available under paragraph (1).
[snip]
(f) Requirement To Preserve Evidence.—
(1) In general.— A provider of wire or electronic communication services or a remote computing service, upon the request of a governmental entity, shall take all necessary steps to preserve records and other evidence in its possession pending the issuance of a court order or other process.
(2) Period of retention.— Records referred to in paragraph (1) shall be retained for a period of 90 days, which shall be extended for an additional 90-day period upon a renewed request by the governmental entity.
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So you're 100% right: the name, address, etc information is ALREADY being preserved. This legislation mandates that records of IP addresses linked to accounts be stored for at least 18 months, whereas before they would have been retained for 90-180 days.
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[0]: http://www.law.cornell.edu/uscode/18/usc_sec_18_00002703----...