Verizon on Wednesday became the first major US telecom carrier to release a "transparency report," and said it received 320,000 data queries last year in the United States alone.
Verizon also said it received between 1,000 and 2,000 "national security letters" from US officials, and had law enforcement requests in 13 other countries where it has operations.
The big telecom firm last month said it would follow the lead of big technology firms including Google, Apple and Microsoft in issuing the transparency reports.
The companies have been under scrutiny in light of revelations of wide-ranging US government surveillance programs.
AT&T also said last month it would issue a transparency report.
Verizon said its 2013 data for the United States included subpoenas, court orders, warrants and emergency requests from law enforcement.
"We do not release customer information unless authorized by law, such as a valid law enforcement demand or an appropriate request in an emergency involving the danger of death or serious physical injury," the company said in the report.
More than 164,000 of the requests were subpoenas from US law enforcement, which Verizon said compelled the company to comply.
"The subpoenas we receive are generally used by law enforcement to obtain subscriber information or the type of information that appears on a customer's phone bill," the company said.
"More than half of the subpoenas we receive seek only subscriber information: that is, those subpoenas typically require us to provide the name and address of a customer assigned a given phone number or IP address."
It also received more than 70,000 court orders signed by a US judge and 36,000 warrants which require probable cause that the data sought is linked to a crime, Verizon said.
More than 50,000 cases were emergency requests for information from law enforcement, it added.
Outside the United States, the largest number of requests came from Germany (2,996) and France (1,347), Verizon said.
The company said it did not track the percentage of cases where it provided data, but will do so in the future.
Verizon said it would reject a request in cases where a demand "is facially invalid" or "overly broad or vague."
The companies are not allowed to disclose requests from the secret Foreign Intelligence Surveillance Court, but tech firms have been pressing for permission to reveal this data.
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