Is there a reason why IMEI is stored in EEPROM?

Question

I've heard that IMEI numbers are stored on an EEPROM, essentially letting them be erased and rewritten. Thieves misuse it to make stolen phones untraceable. Is there a reason why manufacturers don't use one-time programmable non-volatile memory for this?

score 3 · Answer 1 · answered Apr 13 '15 at 11:16

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In some countries (I think China is one), regulations require the phone's IMEI to change each time it's repaired.

answered Apr 13 '15 at 11:16

Justin King-Lacroix

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Interesting, surely this defeats the point of network barring? – AStopher Aug 10 '15 at 22:24
Huh. Yeah, good point. Although network barring is a giant fractured mess anyway. – Justin King-Lacroix Aug 10 '15 at 22:38

score 3 · Accepted Answer · answered Apr 13 '15 at 19:27

Manufacturing costs are the primary driver of this flexibility. While phones often have many names on the outside, on the inside, there are a much smaller number of actual hardware manufacturers. Since one hardware builder has to create kit for several OEMs, it is much easier to build the systems with EEPROMs that can be reflashed again and again, so that product which fails a test while being built for Manufacturer A, can be reworked, reflashed, and end up shipping for Manufacturer B.

In the olden days, when on-board ethernet was a new thing, MAC addresses were originally distributed as you suggest, on non-modifiable chips. This meant that when a partially completed board made it up to test, and it was determined to be faulty, the company building on-board ethernet devices for manufacturers A and B had to keep a log book of all the thrown-away MAC addresses, so that more chips could be burnt, so those addresses wouldn't be 'wasted'. Once they moved to putting MAC's in EEPROMs, failures could be reworked, while the MAC addresses were returned to the pool of available numbers instantly.

Is there a reason why IMEI is stored in EEPROM?

2 Answers2