01 September 2009

Problems with caller ID

Obtaining caller ID, processing it and displaying it is actually a fairly complex process involving the caller's operator, yours, your SIM and your phone's software.

If all you see when someone calls you is "Call 1" or "Private number", no actual phone number, then you're not receiving caller ID at all. This can be because the caller is in fact concealing their number (you can do this on a GSM phone by prefixing the number to dial with #31#). In this case, there's nothing you can do.

If the caller IS sending out their caller ID but you're not receiving it, then the problem lies with your network and/or with your SIM. Give your operator a call. The chances are they can remedy this with an over-the-air update of your SIM card.

If you are now receiving caller ID but your phone isn't displaying the corresponding contact's name, it's because it can't tell whose number it is. There are many possible reasons for this, the three most common being duplicate numbers, international format and operator-branded firmware. There's also a quirk in SymbianOS that can potentially come into play.

If multiple contacts have the same number in your contacts list and one of them calls you, your phone has no way of knowing which one is actually on the other end of the line and, quite sensibly, just shows the number instead of trying to "guess" who it really is. Now, most phones can store contacts both in their own memory and on the SIM card. If you have the same contact in both locations then that counts as duplicates and you'll never see that contact's name displayed. The cure for this is to use the phone's built-in search facility and to search for the number in question. If you find it more than once then you'll have to delete all but one occurrance.

Another potential cause is storing the numbers in the "wrong" format. Always store your numbers in international format. Not only does it provide a uniform platform for number detection to work from, it also makes calling your home-country contacts easier from abroad. Assuming you live in the UK as I do and your contact's mobile number is 07890123456, don't store it in your contacts as such, use the international format instead. Prefix the number with a "+" sign (obtained by pressing the "*" key twice in rapid succession on Nokia phones) and the international prefix ("44" in the case of the UK) and strip the leading zero. You end up with:

+ 44 7890123456 (don't include the spaces, they're printed here for clarity)

In many countries, the UK included, the international dialling prefix is "00", so some people think they can get away with using "00" instead of the "+" sign because they don't know how to enter the latter.

Well, they can't.

The phone won't recognise the number as being an international number because it doesn't start with a "+" and therefore won't be able to do a certain number of automatic transformations. Also, it won't work in all countries. In the USA, for example, the international prefix is "01", not "00", so if you take your phone over to the USA and try to ring someone at home, you won't get through and you might also incur roaming charges. It has to be a "+" sign.

Also bear in mind that synchronising with Outlook tends to mess up numbers. Microsoft very helpfully add spaces and a "(0)" in the number sometimes to make it easier for humans to read. It does however mean that the number is altered and therefore incorrect.

Finally, quite a few problems of this nature are down to operators messing things up when they alter the firmware in handsets that they distribute (read here for more information). In some cases it is possible to get written permission from the network operator to remove their buggy firmware and install generic Nokia firmware in its place in order to eliminate this problem (and others besides), but it's far from easy in an industry so tightly controlled by the networks. Characteristic tell-tale signs of operator ineptitude are the phone being able to display the contact's name when that contact calls you but not when they text you, or vice-versa, depending on whether you've stored the contact's number in international format or not.

There is also a bit of silly "optimisation" in SymbianOS itself, which can rear its ugly head from time to time. The operating system only compares the last 7 digits of the caller ID number it's receiving with entries in its contacts list. The probability of two people sharing the same 7 digits at the end of their phone number is one in ten million, but it has been known to happen. In this case, the phone can't distinguish between the two. So, for example, +441204123456 and +33634123456 are percieved as being the same number when they're clearly even in different countries (the UK and France). If one of those calls you or sends you a text message then the name will not be displayed because the phone doesn't know which one it is.

Caller ID in text messages is also a bit of a problem sometimes.

Assuming the phone is clear of operator-induced problems (see above), if it can't identify the contact correctly when they're calling you, it won't be able to identify them any better when they text you. So, you fix the problem, and yet the text message you received earlier still shows a number as the sender and not the contact that the phone is now able to identify correctly. Why is that?

It's because the list of messages displayed is built as and when inbound messages arrive. It is not updated every time you look at the list (think of the overhead that would be for phones with thousands of messages in the list!). The phone was not able to identify the contact at the time the message was received, so that's how it stays.

So, in short:

1) Eliminate duplicate entries, including on the SIM card.
2) Make sure all your numbers are in international format with "+" as the international dialling prefix.
3) If problems persist then it's related to operator branding.
4) SymbianOS only looks at the last 7 digits of phone numbers.
5) SMS/MMS message lists are built as and when messages are added, not in real time.

7 comments:

rxerri said...

checked everything you said.

deleted all sim entries
all number start with +
phone is sim free from factory
last 7 digits are different

can't understand why a 600 euro mobile phone cannot display contact names. really digusting and dissapointing!!. i think this will be the end of my relationship with nokia. had nokia phones for 10 years now. N95 was and still is the best of the N series

Rodney

Florence said...

Thank you very much for sharing this in-depth knowledge! It's very kind of you and most helpful!

G. Stewart said...

Glad it helped :)

Michele said...

I had this problem on my Nokia N97 mini too.
I've found a partial solution to this problem.

I checked all your advices and tested my Nokia N97 mini for several days.
From my tests i have found this sort of bug: when i turn on the phone, only the first incoming call doesn't show the name.
Then the next incoming calls work well.
I think it's a bug. It seems that when the phone starts, it doesn't load the saved phone numbers...
Maybe the phone load them only after the first incoming call.
All this happen only with incoming call; with the SMS is all ok.
It's seems a strange bug.

In the end, the my solution against this bug is don't turn off the phone...
I hope that the nokia developers will solve this frustrating problem with the next firmware release.

@ rxerri
You're right but, but you have to know that as mobile phone grow more complex, bugs become more common and difficult to fix.
This is a law of computer science...

pu said...

thank for the article, very helpful

it is just a problem that Nokia does not want to fix, it happens to all the most relased nokia smart phone.

I am living in Australia, I am using a Nokia 5530 ( Symbian S60V5), we have 10 digits mobile number here, the only way i fixed my phone is to creat duplicate numbers, one with normal 10 digits number for phone calls, and another wil +61digits for sms/mms, it is the only way to fix it. as the mobile network here is operated as they do not send +61 country codes when you make phone calls but does when you send sms/mms, it is frustrating i know, and Nokia's software has been great except this "simple contact problems" that a cheap 100 dollars other brand phones have no such problems. imagine people spend like 800 dollars on a N97 and find out this, how disappointing it is !

i think my next phone will be away from Nokia as well.

GLEN MICHAEL said...

another way to get around the duplicate number problem is to select the option to use only one source for contacts(you can select SIM/phone memory/or both)the best is to use the phone memory as there are a lot more options of what you can do with a contact (multi numbers/notes/image & ringtone ect). if you are starting out with a new phone and your contacts are on your old SIM all you have to do is go your contact list, select all, then select copy to phone memory, then you can got to the option I mentioned before (use phone memory only). the numbers will still be in your SIM as a non-updated backup but will not be visible to the phone OS.

G. Stewart said...

Absolutely. However, it doesn't cater for the eventuality that you have more than one contact in the same memory with the same number. Eg. both Mum and Dad sharing the same land line. But you'd rather not just create a contact called "Mum & Dad" because they have separate mobiles.