The mechanical behavior of high strength and abraded (proof test level) optical fibers have been tested by joint experiments at nine laboratories in a wide range of dynamic stress rates and on static stresses. The answers to the open questions about B-value magnitude, measurement method and life time estimation were found (see Conclusions). Although measurement results diverge slightly because of accuracy problems and environmental conditions, the results show that the one-region power-law model cannot describe the test results, but the two region power law theory can. Both nand B-values are dependent on dynamic stress rate and static stress level. For long term life time estimations of optical fibers the B and n-values of Region I shall be used, and they should be evaluated from the test results on fiber weak spots at low stress rates or from static fatigue tests, by using the two region power law theory.