Blacklisted IMEI? - Page 1
Forum section: electronics / general

author: steve30
author_rank: Frequent Contributor
timestamp: January 30, 2014, 06:46:27 am
content: I got an old mobile telephone off ebay a couple of years ago. It works fine with no SIM card, but when I put a SIM card in, it says 'Searching', then changes to 'Registering', then turns itself off.I can't see any explanation for this, so I was wondering, could it be that the telephone's IMEI is blacklisted by the network(s)? Personally, I would have expected an error message or similar, but I think I read somewhere that they can just turn off when this happens.

author: Rerouter
author_rank: Super Contributor
timestamp: January 30, 2014, 07:36:18 am
content: are you sure its not just going flat due to battery ESR, it has to do a bit of back to back transmitting during the registering handshake, which could make it drop out,

author: cybermaus
author_rank: Frequent Contributor
timestamp: January 30, 2014, 07:38:02 am
content: Seems unlikely to me, but if you want to know for sure, go to a place with absolutely no reception (put it in a box clad with alufoil while in a cellar) and turn it on. It it turns on with "no network" message, and then you bring it out and it turns of after it sees a network, it may be true.But I would think its just a fault where the radio somehow shorts or drains a power line sufficiently for a reset.

author: steve30
author_rank: Frequent Contributor
timestamp: January 30, 2014, 08:26:22 am
content: Thanks for the replies. The battery issue sounds very likely, but is not possible because I'm powering it from a bench PSU. The telephone's current seems to peak at about 200mA, but it would need at least 900mA for the PSU's voltage to drop significantly.I unscrewed the retractable antenna and the telephone starts up fine then. It says 'Searching', then it just sits idle, as it can't pick any signal up. If I put the antenna back in, it briefly flashes 'UK Vodafone' and shuts off.It also starts up OK with my Virgin SIM card, but won't find the network because Virgin is on 1800MHz, and the telephone is 900MHz only.

author: cybermaus
author_rank: Frequent Contributor
timestamp: January 30, 2014, 08:44:29 am
content: Hmm, interesting. It still could be a power surge or even firmware problem caused by handshake, but it IMEI block is becoming more of a possibility.What phone did you say it was? Most phones need specialized equipment to change IMEI, but if its a (non-smartphone) based on a Mediatek chipset, I think I have an AT command somewhere. Many cheap Chinese phones used to be build on those chips. (for smartphone Mediatek, it needs to be rooted)

author: steve30
author_rank: Frequent Contributor
timestamp: January 30, 2014, 08:50:27 am
content: If I let the phone start up with no antenna and then put the antenna in, it did a few times actually stick on UK Vodafone. Hmm.The mobile phone is a Motorola D170 (Made in Germany) from the late 1990s. The internet doesn't seem to know much about this model. I got it because our family used to have one years ago and I always loved the industrial design of it. I'm not sure about the chipset. All the semiconductors are under metal cans which are soldered. I'll have a go at desoldering them later as I'm curious to see what's inside.

author: cybermaus
author_rank: Frequent Contributor
timestamp: January 30, 2014, 09:03:51 am
content: Well, soon the 900 GSM band will be discontinued and replaced with 900 UMTS everywhere, so then it can rest peacefully in your collectors cabinet.But until that happens: if you drive closed toward your closest Vodafone 900 mast (not too close) it may work better, as it will reduce transmit power based on how clear and strong it hears the tower.Edit: alternate suggestion: Maybe it sometimes crashes the firmware because in fact nowadays they transmit in (i believe it is called) EGSM, which is a slightly different protocol then GSM. Maybe Vodafone does not properly test backward compatibility with older handsets. Shame on them. They should make sure all 90ies handsets still work

author: steve30
author_rank: Frequent Contributor
timestamp: January 30, 2014, 10:17:16 am
content: Well well well. I thought I'd give the power supply issue another test. I stuck 440uF on the output of the PSU, and now the phone works fine. Fantastic. I dialed a number and a voice told me I had no credit.I guess I can consider this functional then. It still only seems to use just over 200mA when in a call, so it must have made a pretty quick surge. Maybe this is a job for the oscilloscope.Whereabouts are they discontinuing GSM? Haven't heard anything about that here in England.

author: cybermaus
author_rank: Frequent Contributor
timestamp: January 30, 2014, 12:26:31 pm
content: If a cell phone can do that to your PSU, you may want to leave that 440uF in place permanently.

author: Psi
author_rank: Super Contributor
timestamp: January 30, 2014, 01:13:17 pm
content: Cellphones can draw peak currents in the amps range. (Data is sent in very short bursts)Before, when it was switching off, it probably put the PSU into current limit during TX and the vdrop reset the cpu.You'll probably find it works without the cap if you run it from a battery instead of a psu.

author: steve30
author_rank: Frequent Contributor
timestamp: January 31, 2014, 02:24:28 am
content: The telephone is designed to run from AA cells, so I just tried a selection of cells, and I had the same problem with it shutting off, so it probably takes too much current for the cells I have. I'm imagining that this telephone doesn't have a particularly good battery life.I seem to remember having no luck with batteries last time I tried, which is what led me to think that it wasn't a PSU problem, even though it was.Does anyone else here have any 1990s mobile phones in use?

author: Psi
author_rank: Super Contributor
timestamp: January 31, 2014, 03:45:44 am
content: It should be happy with rechargeable AA's, they can supply plenty of current.but there's no reason to leave out the capacitor, it's a good thing to have in circuit to handle the high current peaks.

author: jwm
author_rank: Regular Contributor
timestamp: January 31, 2014, 04:13:31 am
content: Quote from: steve30 on January 31, 2014, 02:24:28 amIs it possible it was designed with the assumption that rechargable batteries would be used in it? They can handle signifigantly more current than alkaline ones. I have some equipment that takes AAAs but specifies rechargable only for that reason.There may also have been a cap inside of it to provide the surge current that dried up, solder your bodge cap in its place.

author: peter.mitchell
author_rank: Super Contributor
timestamp: January 31, 2014, 05:18:26 am
content: Quote from: steve30 on January 31, 2014, 02:24:28 amI've got a Nokia 6110 that I put a lithium battery in, works decent.

author: Zad
author_rank: Super Contributor
timestamp: January 31, 2014, 05:34:12 am
content: Check the details onwww.imei.infoThat should tell you if it is blocked.

author: steve30
author_rank: Frequent Contributor
timestamp: January 31, 2014, 07:31:16 am
content: I popped the metal cans off. Nothing particularly interesting in there.I think I'll try and find a better 'old' mobile phone to use than this one. I only got it as something to have a fiddle with, and I think it has seen better days.

author: tom66
author_rank: Super Contributor
timestamp: January 31, 2014, 09:35:13 am
content: I have a Nokia 3510i which when making a phone call will sometimes cut out with a low battery. I figure battery ESR plus low voltage drops below the low volt threshold when the GSM PA is active...

author: steve30
author_rank: Frequent Contributor
timestamp: January 31, 2014, 12:08:25 pm
content: Quote from: tom66 on January 31, 2014, 09:35:13 amIntriguing. What kind of battery does it have? I have a Nokia 3510i with its original 10 year old Li-Ion battery, and it works fine.

author: Fraser
author_rank: Super Contributor
timestamp: January 31, 2014, 12:26:58 pm
content: I still have four 5110's in a cupboard somewhere..... I always liked that phone.......simple....like me !It may not be true, but I was told recently that some old mobile phones are selling for silly prices on e*ay as new owners of older high spec luxury cars want the correct phone to fit the built in OEM phone cradles that these cars had. Mention was made of one Noka phone selling for over GBP200 !!! May be totally untrue story but I did find it amusing all the same.

author: tom66
author_rank: Super Contributor
timestamp: January 31, 2014, 01:20:17 pm
content: Quote from: steve30 on January 31, 2014, 12:08:25 pmIt works on its original battery, but it's no where near as long lasting as it was originally. It will do about 2 days to a charge in standby, and about 2-3 hours voice calling. (Then again, that's about what my Galaxy S2 does now, so there's technological progress.) It only cuts out when the battery is on its last bar. In standby, it seems to spend a long time there, over 80% of the time. I wonder if it is using true SoC or just estimating capacity from cell voltage.

author: SeanB
author_rank: Super Contributor
timestamp: February 02, 2014, 05:24:38 am
content: BMW and Nokia 6110 is a common car kit as OEM fit. I had the Nokia 8110i and car kit, worked very well even in areas where no other phone would get a hint of signal. Nice was that the cable end even worked on a 1610 brick.

author: steve30
author_rank: Frequent Contributor
timestamp: February 02, 2014, 09:37:55 am
content: I just tested the Motorola phone on the oscilloscope, and it does indeed draw lots of 1A pulses. These cause a voltage drop of a volt or so. I also checked the manual and it specifies either Alkaline or Lithium cells, so I don't know why it wasn't working from my AA cells. JWM mentioned an internal caps, but there doesn't seem to be much in there, at least nothing sizeable. Strange.

author: steve30
author_rank: Frequent Contributor
timestamp: February 16, 2014, 11:33:16 am
content: Just for the record, I thought I'd update this thread.I got another old telephone which uses a similar battery pack to what this D170 requires. I managed to breathe a bit of life back into the pack, and put it in the D170, and it works fine. The phone has been running a day and a half, and I made a few calls on itI can only assume that all my individual NiMH and NiCad cells have too much ESR and/or are too worn out.The battery pack I just put in contains 4x NiMH 'AAAL' cells (length of an AA, diameter of an AAA). The original D170 pack uses 4x AA cells. There doesn't seem to be anything special about the cells.

author: Neganur
author_rank: Unknown
timestamp: February 16, 2014, 07:49:12 pm
content: Quote from: steve30 on January 30, 2014, 08:50:27 amThe TX PA is most likely be drawing too much current, this switches the phone off.EDIT: Also, as already mentioned, expect the phone drawing pulsed current spikes easily above 1.2 A