SONET is an acronym for synchronous optical networking while SDH is an acronym for synchronous digital hierarchy. They are both standard protocols used for the transmission of multiple digital bit streams (multiplex) synchronously through an optical fiber by using lasers.
Hence, both SONET and SDH are interoperable and typically the same standard protocols in telecommunication networks. Also, the SONET is a standardized protocol that is being used in the United States of America and Canada while SDH is an international standard protocols used in countries such as Japan, UK, Germany, Belgium etc.
The synchronous optical networking was developed in 1985 by Bellcore and it was standardized by the American National Standards Institute (ANSI). SDH was developed as a replacement for the plesiochronous digital hierarchy (PDH).
Generally, SONET comprises of four functional layers and these are;
1. Path layer
2. Line layer.
3. Section layer.
4. Physical or Photonic layer.
The SDH comprises of four synchronous transport modules and these are;
1. STM-1: having a basic data rate of 155.52Mbps.
2. STM-4: having a basic data rate of 622.08Mbps.
3. STM-16: having a basic data rate of 2488.32Mbps.
4. STM-64: it has a basic data rate of 9953.28Mbps.
<em>These two standard telecommunications protocols are used to transmit large amounts of network data over a wide range through the use of an optical fiber. </em>
I think it might be 6 to 5 hours but probably a lot more time depending on the person or age. I am guessing, but I think it could really depend on the persons parents or how much they have to be on their own phone.