Do smart transmitters need to be caliberated yearly?

I agree with the answers in here. 

any how many manufacturing have specified the interval period for their product. On other hand many owner they just applay to what Mr.Hassan Idami says

It depends on client. For some clients , calibration validity is six months. For others it is one year validity.

Calibration frequency depends on a number of factors including:

• Accuracy requirements set by customers
• Requirements set by contract or regulation
• Inherent stability of the specific instrument or device
• Environmental factors that may affect the stability