Simplify the following text for a Grade 11 native English-speaking person.
Original: In 1906 , at the second International Radiotelegraphic Convention in Berlin , an extensive collection of Service Regulations was developed to supplement the main agreement , which was signed on November 3 , 1906 , becoming effective on July 1 , 1908 .
Simplified: In 1906 , the second International Radiotelegraphic Convention was held in Berlin . This convention developed many Service Regulations to be added to the main agreement , which was signed on November 3 , 1906 , and became effective on July 1 , 1908 .