Raghu,

If the equipment is "designed", not "tested" there is no need for calibration.

Digital components working within the specs will work reliably - or fail blatantly - for the life of the equipment.

Do note that an oscillator is an analog function (with digital output). If you have to bring something in to calibrate the oscillator, you have chosen the wrong oscillator.

By the way, having your customers pay every 6 months for 'calibration' seems like a nice revenue generator.

Erik