Method for configuring a wireless device for using voice over lte

Method for a wireless device of providing a voice service via packet switched communication with an operating cellular network, being the cellular network the wireless device is operating in,

• wherein the wireless device is physically connected to an identification unit, said identification unit comprising a first memory block for storing at least one set of configuration parameters for said voice service within a first cellular network, the first cellular network according to the identification unit is different from the operating cellular network, hereinafter the visited cellular network,
• further the wireless device is camping on a base node of the visited cellular network,
• the method comprising the step for the wireless device of:
• prior to setting up a voice call, checking with the identification unit if a set of configuration parameters applicable to the visited cellular network is available,
• if not, requesting said configuration parameters from a parameter server accessible for the visited cellular network by means of routing information,
• receiving said configuration parameters from said parameter server,
• storing at least a portion of received configuration parameters in a second memory block of the identification unit,
• if the configuration parameters are available, or previously received from the parameter server:
• applying said configuration parameters to the wireless device,
• setting up a voice call using said configuration parameters.