the cases in which device provider 70 operates an cms such as d cms 86 or even s cms 76 itself on behalf of service provider 66 or acts as relay in the interactions between the s cms 76 and telephone 78 the negotiation can be set up so that the cms being operated by device provider 70 can extract a service plan identifier from s cms 76 this could be done for example using an https or similar well known means with device provider 70 sending the device id of telephone 78 to be mapped to s cms 76 with service provider 66 returning the corresponding service instance id for that device and corresponding user service plan and profile data corresponding to user u telephone device id and service instance id can be crafted for example with encryption hash or other technology so that they can only have been created by the device provider 70 to service provider 66 respectively for example the device id could be a hash of the device mac address and the service id could be a hash of the user 39 s sip address of record u201c aor u201d these encrypted ids can act as the non repudiateable id set for billing purposes b another case is one in which device provider 70 will expect service provider 66 to supply device provider 70 with the non repudiateable id this is exemplified by the u201c service provider registered device ids u201d and u201c user registered device ids u201d scenarios previously.