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Technology

Electronic serial numbers (ESNs) were created by the U.S. Federal Communications Commission (FCC) to uniquely identify mobile devices, from the days of AMPS in the United States starting in the early 1980s. The administrative role was taken over by the Telecommunications Industry Association in 1997 and is still maintained by them. ESNs are currently mainly used with CDMA phones (and were previously used by AMPS and TDMA phones), compared to International Mobile Equipment Identity (IMEI) numbers used by all GSM phones.[1]

The first 8 bits of the ESN was originally the manufacturer code, leaving 24 bits for the manufacturer to assign up to 16,777,215 codes to mobiles. To allow more than 256 manufacturers to be identified the manufacturer code was extended to 14 bits, leaving 18 bits for the manufacturer to assign up to 262,144 codes. Manufacturer code 0x80 is reserved from assignment and is used instead as an 8-bit prefix for pseudo-ESNs (pESN). The remaining 24 bits are the least significant bits of the SHA-1 hash of a mobile equipment identifier (MEID). Pseudo-ESNs are not guaranteed to be unique (the MEID is the unique identifier if the phone has a pseudo-ESN).

ESNs are often represented as either 11-digit decimal numbers or 8 digit hexadecimal numbers. For the decimal format the first three digits are the decimal representation of the first 8 bits (between 000 and 255 inclusive) and the next 8 digits are derived from the remaining 24 bits and will be between 00000000 and 16777215 inclusive. The decimal format of pseudo ESNs will therefore begin with 128. The decimal format separately displays 8 bit manufacturer codes in the first 3 digits, but 14 bit codes are not displayed as separate digits. The hexadecimal format displays an ESN as 8 digits and also does not separately display 14 bit manufacturer codes which occupy 3.5 hexadecimal digits.

As ESNs have essentially run out, a new serial number format, MEID, was created by 3GPP2 and was first implemented by Verizon in 2006. MEIDs are 56 bits long, the same length as the IMEI and, in fact, MEID was created to be a superset of IMEI. The main difference between MEID and IMEI is that the MEID allows hexadecimal digits while IMEI allows only decimal digits – "IMEI shall consist of decimal digits (0 through 9) only".[2]

The last of the previously unused ESN codes were allocated in November 2008.[3] Applications for assignments were accepted until June 30, 2010 using reclaimed ESN codes, those previously assigned to AMPS or TDMA phones and therefore not present on CDMA2000 systems. Reclaimed codes have also been used for UIMID assignments. Codes are assigned according to industry guidelines.[4]

Although ESN assignments may still occur in the future based on applications received before June 30, 2010, there have not been any assignments made since December 31, 2010.

References[edit]

External links[edit]


Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/Electronic_serial_number — Please support Wikipedia.
This page uses Creative Commons Licensed content from Wikipedia. A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia.

300 news items

Computerworld

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Arizona Daily Star

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Mon, 14 Sep 2015 19:10:39 -0700

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Yahoo Tech

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Thu, 06 Aug 2015 04:31:00 -0700

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Tom's Guide

Tom's Guide
Wed, 14 Oct 2015 09:30:00 -0700

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Fox News

Fox News
Wed, 18 Nov 2015 10:01:41 -0800

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9 to 5 Mac (blog)

9 to 5 Mac (blog)
Tue, 25 Aug 2015 11:12:19 -0700

The status of an iPhone can be checked using a device-specific serial number that's called an IMEI (International Mobile Equipment Identity) number, ESN (Electronic Serial Number), or MEID (Mobile Equipment Identifier). IMEIs have traditionally been ...

Police News

Police News
Thu, 03 Sep 2015 13:37:15 -0700

Verizon Wireless and Sprint use CDMA-compatible technology, and identify their phones with Mobile Equipment Identifier (MEID) or Electronic Serial Number (ESN) numbers. These identifiers let the carrier blacklist a stolen cellphone after a consumer ...

BBC News

BBC News
Thu, 03 Sep 2015 16:03:45 -0700

The US justice department says federal agencies will have to obtain search warrants to use technology that tracks mobile phones under new guidance. Until now agencies such as the FBI had not needed a warrant to use machines called cell-site simulators ...
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