What is claimed is:1. A method in a user equipment for determining whether to transmit network slice selection assistance information to a network as part of radio connection establishment signaling, the method comprising:receiving at an access stratum layer in the user equipment an indication from the network as to whether the network slice selection assistance information stored in a non-access stratum layer is required to be included in the radio connection establishment signaling associated with establishing a connection;activating the transmission of the network slice selection assistance information from the user equipment to the network in the radio connection establishment signaling, when the network slice selection assistance information is determined to be required, or deactivating the transmission of the network slice selection assistance information from the user equipment to the network in the radio connection establishment signaling, when the network slice selection assistance information is determined to not be required;informing the access stratum layer by the non-access stratum layer about the network slice selection assistance information during an initiation of service request procedure when the user equipment is in a connection management idle state; andtransmitting the network slice selection assistance information in the radio connection establishment signaling to the network, when the transmission of the network slice selection assistance information is activated.2. The method according to claim 1, wherein the indication from the network includes system information received from a cell of the network.3. The method according to claim 2, wherein the system information received from a cell of the network is broadcasted system information, which is received while the cell of the network is operating as a serving cell.4. The method according to claim 1, wherein the indication from the network includes radio resource control signaling from the network.5. The method according to claim 4, wherein the indication from the network included as part of the radio resource control signaling from the network is included as part of a radio resource control connection setup message.6. The method according to claim 1, wherein transmission of the network slice selection assistance information in the radio connection establishment signaling is included as part of a radio resource control connection complete message.7. The method according to claim 1, wherein the access stratum layer in the user equipment is configured to inform the non-access stratum layer as to whether the network slice selection assistance information is required or not.8. The method according to claim 1, wherein the signaling information includes a parameter which is always present that can include an associated value that selectively identifies between an indication that network slice selection assistance information for all allowed slices needs to be included in the radio connection establishment signaling, an indication that network slice selection assistance information is included in the radio connection establishment signaling for at least the slices for which a packet data unit connection is to be activated, and an indication that network slice selection assistance information does not need to be included.9. The method according to claim 1, wherein the signaling information includes a parameter which is optionally present, where when present the value of the parameter can distinguish between an indication that network slice selection assistance information for all allowed slices needs to be included in the radio connection establishment signaling, and an indication that network slice selection assistance information is included in the radio connection establishment signaling for at least the slices for which a packet data unit connection is to be activated, and where when absent can serve as an indication that network slice selection assistance information does not need to be included.10. The method according to claim 1, wherein when the radio connection establishment signaling is part of an attempt to resume a connection from an inactive state, the determination as to whether network slice selection assistance information is required should be based upon system information from the cell that is to currently operate as a serving cell.11. The method according to claim 1, wherein the transmission of the network slice selection assistance information is activated, when the user equipment transitions from an old cell that does not require network slice selection assistance information to a new cell that requires network slice selection assistance information, or if the system information associated with a current cell changes to include an indication that network slice selection assistance information is required.12. The method according to claim 1, wherein the transmission of the network slice selection assistance information is deactivated, when the user equipment transitions from an old cell that requires network slice selection assistance information to a new cell that does not require network slice selection assistance information, or if the system information associated with a current cell changes to include an indication that network slice selection assistance information is no longer required.13. A user equipment in a communication network, the user equipment comprising:a transceiver that receives an indication from the network at an access stratum layer in the user equipment as to whether the network slice selection assistance information stored in a non-access stratum layer is required to be included in the radio connection establishment signaling associated with establishing a connection; anda controller, where the transmission of the network slice selection assistance information from the user equipment to the network in the radio connection establishment signaling is activated by the controller, when the network slice selection assistance information is determined to be required, and where the transmission of the network slice selection assistance information from the user equipment to the network in the radio connection establishment signaling is deactivated by the controller, when the network slice selection assistance information is determined to not be required;wherein the controller further informs the access stratum layer via the non-access stratum layer about the network slice selection assistance information during an initiation of service request procedure when the user equipment is in a connection management idle state; andwherein the network slice selection assistance information is transmitted in the radio connection establishment signaling to the network by the transceiver, when the transmission of the network slice selection assistance information is activated.14. The user equipment according to claim 13, wherein the indication from the network includes system information received from a cell of the network.15. The user equipment according to claim 14, wherein the system information received from a cell of the network is broadcasted system information, which is received while the cell of the network is operating as a serving cell.16. The user equipment according to claim 13, wherein the signaling information includes a parameter which is always present that can include an associated value that selectively identifies between an indication that network slice selection assistance information for all allowed slices need to be included in the radio connection establishment signaling, an indication that network slice selection assistance information is included in the radio connection establishment signaling for at least the slices for which a packet data unit connection is to be activated, and an indication that network slice selection assistance information does not need to be included.17. The user equipment according to claim 13, wherein the signaling information includes a parameter which is optionally present, where when present the value of the parameter can distinguish between an indication that network slice selection assistance information for all allowed slices need to be included in the radio connection establishment signaling, and an indication that network slice selection assistance information is included in the radio connection establishment signaling for at least the slices for which a packet data unit connection is to be activated, and where when absent can serve as an indication that network slice selection assistance information does not need to be included.18. The user equipment according to claim 13, wherein when the radio connection establishment signaling is part of an attempt to resume a connection from an inactive state, the determination as to whether network slice selection assistance information is required should be based upon system information from the cell that is to currently operate as a serving cell.19. The user equipment according to claim 13, wherein the transmission of the network slice selection assistance information is activated, when the user equipment transitions from an old cell that does not require network slice selection assistance information to a new cell that requires network slice selection assistance information, or if the system information associated with a current cell changes to include an indication that network slice selection assistance information is required.20. The user equipment according to claim 13, wherein the transmission of the network slice selection assistance information is deactivated, when the user equipment transitions from an old cell that requires network slice selection assistance information to a new cell that does not require network slice selection assistance information, or if the system information associated with a current cell changes to include an indication that network slice selection assistance information is no longer required.