A system comprising: an access node and a received node; wherein the access node is configured to couple to the receiver node and to send a relative time-of-day value via a channel to the receiver node, wherein the receiver node comprises a customer node, wherein the access node is located at a digital subscriber line central office, wherein the customer node is a customer premise equipment that is coupled to the CO, and wherein the channel is an Embedded Operations Channel or overhead frames; wherein the relative TOD value is a value of a time instant modulo a fixed value, wherein the time instant is when a signal transmitting to the customer node arrives at a reference point at the access node side, wherein the relative TOD value is used for frequency synchronization of a clock in the receiver node with a clock in the access node; characterized in that the customer node obtains a relative TOD' value, adjusts the clock in the customer node with the relative TOD' values and the relative TOD values received from the access node to frequency synchronization with the clock at the access node; wherein the relative TOD' value is a value of a time instant when the same signal for which the relative TOD value is obtained arrives at a reference point at the customer node side modulo a second fixed value, and wherein adjusting the clock in the customer node with the relative TOD' values and the relative TOD values received from the access node comprises estimating a change in an offset between the relative TOD value and the relative TOD' value from a present super frame period to a previous super frame period, adjusting the clock in the customer node with the change in the offset. an access node and a received node; wherein the access node is configured to couple to the receiver node and to send a relative time-of-day value via a channel to the receiver node, wherein the receiver node comprises a customer node, wherein the access node is located at a digital subscriber line central office, wherein the customer node is a customer premise equipment that is coupled to the CO, and wherein the channel is an Embedded Operations Channel or overhead frames; wherein the relative TOD value is a value of a time instant modulo a fixed value, wherein the time instant is when a signal transmitting to the customer node arrives at a reference point at the access node side, wherein the relative TOD value is used for frequency synchronization of a clock in the receiver node with a clock in the access node; characterized in that the customer node obtains a relative TOD' value, adjusts the clock in the customer node with the relative TOD' values and the relative TOD values received from the access node to frequency synchronization with the clock at the access node; wherein the relative TOD' value is a value of a time instant when the same signal for which the relative TOD value is obtained arrives at a reference point at the customer node side modulo a second fixed value, and wherein adjusting the clock in the customer node with the relative TOD' values and the relative TOD values received from the access node comprises estimating a change in an offset between the relative TOD value and the relative TOD' value from a present super frame period to a previous super frame period, adjusting the clock in the customer node with the change in the offset.