+CLIP when no CLI available

Using a UK Vodafone pre-pay SIM, it seems that no +CLIP: indication is given at all when the caller withholds their number.

Is there a way to get the +CLIP: indication showing that the number has been withheld or is not available?
(it looks like the parameter should show this).

Is this network-dependent?


Just confirmed my recollections using a Telstra (Australia) SIM - I don’t get any +CLIP indications when the calling party’s number is withheld.

See also this post.

I had a look through my code where I dealt with this, and I have to do the following:

  • on startup, set my calling number CLID string to NULL
  • register for +CLIP events - set the CLID string in event handler
  • register for inbound call ‘RING’ events
  • After two RING events, check the CLID string is not NULL (have number) else calling number is withheld
  • On hangup event, release CLID string and set to NULL

This of course is made far more difficult than it needs to be, as the only way to get to the CLID is via +CLIP - there’s no API to do it :frowning:

ciao, Dave


I have a customer using a T-mobile UK sim card used within a Q2687RD module.
When he makes a ring, the +CLIP is not presented.
However, if I make a ring from italy the +CLIP is presented and my number is showed.

The question:
-is it a problem of the operator of the sim card (in this case T-Mobile UK, but I have also another with same issue and Vodafone UK sim card)?


-is it a problem of the customer phone/operator which withhold the number (I don’t think so because they used 20 different numbers)?



A couple of things:

  1. CLID is sent by the operator, not by the sending device
  2. The sending device can indicate to the operator that the number is to be blocked from the receiving device; or the network can otherwise not send the number (i.e. the number is marked as ‘private’ for some other reason).
  3. The CLID data is sent to the receiving device between the first and second ring events - so if you answer the call (ATA) too early, then you won’t get the CLID data.
  4. Some operators don’t send the CLID by default, or it’s an extra service that has to be paid for. Check how the receiving SIM is setup with the operator.

So … some things to check:

  1. Has your customer had the CLID information blocked on their SIM/number? Check by ringing another mobile and seeing if the correct number is displayed.
  2. Check that you have the correct unsolicited messages set up on the Q2686 - or the CLID won’t be passed on to the device.

Hope this helps.

ciao, Dave

Note also that CLI can be “lost” at the “boundaries” between different networks - in particular, across national boundaries