The disclosures relates to a method of provisioning a subscriber profile into a subscriber data store of an IP Multimedia System (IMS) capable telecommunications network, the subscriber profile being for a subscriber which is a visiting subscriber with respect to the IMS-capable telecommunications network, the subscriber data store being for use in IP Multimedia System (IMS) call processing, the method comprising: receiving a request to allocate an IMS Access Point Name (APN); and in response to receiving the request to allocate the IMS APN, triggering a provisioning of the subscriber profile into the subscriber data store.