Is it possible concurrent editing of xls in addition to GoogleDrive?

Worker in the nth branch is required concurrent editing of a single table. Roughly speaking, the secretaries conduct telephone calls and to the DB to add the value "pozvoleno". At the moment, using Microsoft Office and xls files, which leads naturally to problems of parallelization, because the second opened file can be opened in "read-only". A good way would be Google Drive, but the problem must be a stable Internet connection, which in this location can not be, and when GD turns into a very ordinary office that synchronization will solve problems at the root, i.e., in favor of one or another of the file with the replacement (am I right here?)


Probably would be Feng Office, but:
"At the moment there is a second project for OpenGoo at the University, developed by students Fernando Rodríguez, Ignacio Vázquez and Juan Pedro del Campo.[6] Their project aims to create a free web spreadsheet."(C) Wiki about FangOffice


Of course, there is always remain, but people have to retrain, plus once in red to import already existing databases. Are there alternatives, or is it possible the house is to build GD?