An apparatus, comprising: at least a first SIM module configured to access a first wireless carrier and a second SIM module configured to access a second wireless carrier; at least a first RF modem configured to communicate with the first wireless carrier and a second RF modem configured to communicate with the second wireless carrier; at least one global navigation satellite system receiver; at least one processor (215, 215', 305A, 305B); at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to: compute a reference global navigation satellite system-cellular frame time relation between received satellite signals and cellular frame signals received by the second RF modem from a base station of the second wireless carrier; cause a handover to be performed from a first base station to a second base station of the first wireless carrier; cause an inter-modem frame trigger to be sent from the second RF modem to the first RF modem, to synchronize the first RF modem with the cellular frame signals received from the base station of the second wireless carrier; compute a current global navigation satellite system-cellular frame time relation between the received satellite signals and cellular frame signals received by the first RF modem from the second base station of the first wireless carrier by computing a cellular frame time difference between the base station of the second wireless carrier and the second base station of the first wireless carrier, and adding that difference to the reference frame time relation of the received satellite signals with the base station of the second wireless carrier; and determine position using the received satellite signals and the cellular frame signals received by the first RF modem from the second base station of the first wireless carrier, based on the computed current global navigation satellite system-cellular frame time relation. at least a first SIM module configured to access a first wireless carrier and a second SIM module configured to access a second wireless carrier; at least a first RF modem configured to communicate with the first wireless carrier and a second RF modem configured to communicate with the second wireless carrier; at least one global navigation satellite system receiver; at least one processor (215, 215', 305A, 305B); at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to: compute a reference global navigation satellite system-cellular frame time relation between received satellite signals and cellular frame signals received by the second RF modem from a base station of the second wireless carrier; cause a handover to be performed from a first base station to a second base station of the first wireless carrier; cause an inter-modem frame trigger to be sent from the second RF modem to the first RF modem, to synchronize the first RF modem with the cellular frame signals received from the base station of the second wireless carrier; compute a current global navigation satellite system-cellular frame time relation between the received satellite signals and cellular frame signals received by the first RF modem from the second base station of the first wireless carrier by computing a cellular frame time difference between the base station of the second wireless carrier and the second base station of the first wireless carrier, and adding that difference to the reference frame time relation of the received satellite signals with the base station of the second wireless carrier; and determine position using the received satellite signals and the cellular frame signals received by the first RF modem from the second base station of the first wireless carrier, based on the computed current global navigation satellite system-cellular frame time relation. compute a reference global navigation satellite system-cellular frame time relation between received satellite signals and cellular frame signals received by the second RF modem from a base station of the second wireless carrier; cause a handover to be performed from a first base station to a second base station of the first wireless carrier; cause an inter-modem frame trigger to be sent from the second RF modem to the first RF modem, to synchronize the first RF modem with the cellular frame signals received from the base station of the second wireless carrier; compute a current global navigation satellite system-cellular frame time relation between the received satellite signals and cellular frame signals received by the first RF modem from the second base station of the first wireless carrier by computing a cellular frame time difference between the base station of the second wireless carrier and the second base station of the first wireless carrier, and adding that difference to the reference frame time relation of the received satellite signals with the base station of the second wireless carrier; and determine position using the received satellite signals and the cellular frame signals received by the first RF modem from the second base station of the first wireless carrier, based on the computed current global navigation satellite system-cellular frame time relation.