Level 2: Rookie

No Caller ID name display for Incoming International Calls

I'm sorry this explanation is so long winded. Although the issue is relatively simple it is quite complex to explain adequately.


I've recently switched to the NBN with Telstra. Previously on the old analogue PSTN line my Uniden DECT phones had no problem matching the caller ID number with the phone number stored in the phone book and displaying the caller's name. Since changing to the NBN and connecting the DECT phones via the telephone outlet on the modem (Telstra Gateway Max 2) this no longer works for incoming international calls.


Closer investigation has revealed that there is a difference between the caller ID information supplied on the NBN connection to that supplied on the old analogue connection. With the old analogue connection for a call from the UK. it would send:


i.e. the country code followed by the 10 digit UK phone number - a total of 12 digits.


With the new NBN connection for a call from the UK it sends:


i.e. the Australian international prefix plus the country code followed by the 10 digit UK phone number - a total of 16 digits.


The problem is caused because the DECT phone only accepts up to 15 digits for a caller ID, therefore the last digit gets truncated and there is no match with the phone book entry.


When the DECT phone performs the phone book lookup it does this in a right justified manner, i.e. it starts comparing the two numbers starting with the last digit and working backwards through the numbers. This is necessary because phone book entries may be stored with or without area codes etc. For example the following two numbers match even though they are different:


0711112222        Caller ID string

    11112222        Phone book entry


For international numbers the following numbers also match:

        441234567890        Caller ID string from old PSTN

0011441234567890        Phone book entry


But as only the first 15 digits of the caller ID get passed through the following will never match:

  001144123456789        Caller ID string from NBN

0011441234567890        Phone book entry


Most phones with the caller ID feature work this way. They do not expect international access codes to prefix the caller ID string.


So, finally, here is my question: Can you please turn off the insertion of the leading 0011 in the caller ID string for incoming international numbers on the NBN? You didn't supply before on the PSTN so why do it now? It is certainly not part of the caller ID provided by the overseas telco. It is the Australian specific international access code, which is only relevant for outgoing calls anyway, it is not actually part of the incoming number.


So if it is being "artificially" inserted, surely it can be disabled. Please just send me 12 digits (441234567890) like it always was before - with no international access code prefix.

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Telstra (Retired)
Telstra (Retired)

Re: No Caller ID name display for Incoming International Calls

Thanks for taking the time to let us know about this. I will see what I can find out and if this is something that we are able to resolve or if it is part of the network. 


- Shelly

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Level 2: Rookie

Re: No Caller ID name display for Incoming International Calls

Finally heard back from Tech Support and they stated that it is working as designed.


The reason is so that the number from the caller ID string can be used for direct callback if required. This would not be possible if the international prefix (0011) was omitted.


I accept that this is true and possibly a very useful feature, but I wonder why previously for years on the analogue PSTN it was just fine to only send the number starting with the country code?


Looks like I will be buying a new set off DECT Phones!


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