In some examples, a device detects a calling identifier received as part of initiating a call matches an emergency identifier, the emergency identifier associated with information from which to derive a Uniform Resource Name (URN). The device detects that the device is in a first network different from a second network, where the second network configured the emergency identifier. In response to detecting that the device is in the first network different from the second network, the device includes a URN, urn:service:sos, in a Session Initiation Protocol (SIP) INVITE message to be transmitted.