Martin Further to our conversation on this topic in Berlin I now respond formerly on the list. 3GPP has defined the mobile terminal as performing the UA role since the very beginning of IMS. Therefore the mapping between the terminal and the instance ID in IMS is a one to one relationship. Andrew ----- Original Message ----- From: Martin Thomson [mailto:martin.thomson@xxxxxxxxx] Sent: Monday, July 22, 2013 12:57 PM Central Standard Time To: Andrew Allen Cc: tbray@xxxxxxxxxxxxxx <tbray@xxxxxxxxxxxxxx>; ietf@xxxxxxxx <ietf@xxxxxxxx> Subject: Re: Last call: draft-montemurro-gsma-imei-urn-16.txt On 20 July 2013 15:34, Andrew Allen <aallen@xxxxxxxxxxxxxx> wrote: > There are obviously always alternative design choices but why would you want to include both a pre assigned device ID and a generated device ID in the same message? I think that reading this thread should provide you with ample reasons. The instance ID in outbound has certain stability requirements that do not strictly correspond to the lifetime of the hardware in use. The other use cases answer very different questions, which include: is this a stolen device, is this device authorized to use the networks, etc... I'm certain those questions can be answered without a device identifier traversing the network. --------------------------------------------------------------------- This transmission (including any attachments) may contain confidential information, privileged material (including material protected by the solicitor-client or other applicable privileges), or constitute non-public information. Any use of this information by anyone other than the intended recipient is prohibited. If you have received this transmission in error, please immediately reply to the sender and delete this information from your system. Use, dissemination, distribution, or reproduction of this transmission by unintended recipients is not authorized and may be unlawful.