We disclose an interface device configured to inter-convert CPRI data frames and Optical Transport Units (OTUs). The interface device acquires frame synchronization by temporarily storing data in a buffer bank such that translated sync characters are placed at respective predetermined locations within the buffer bank. Each translated sync character represents, in the corresponding OTU, a respective sync character of a CPRI hyperframe. The interface device is configured to distinguish translated sync characters from payload-data words of identical value based on predetermined alignment, in the buffer bank, of data temporarily stored therein for conversion into the CPRI data format. The interface device advantageously enables multiplexing of a plurality of CPRI links and aggregation and encapsulation of the multiplexed CPRI data into a stream of OTUs for transmission to the intended destination over an Optical Transport Network.