One source said the job cuts range would run into four figures.
The Handelsblatt newspaper in Germany had reported Siemens would slash 1,000 jobs as part of a possible sale of the unit.
Siemens will present restructuring details to labour representatives today, another source said.
Siemens finance chief Joe Kaeser said in January it would spin off SIS and did not rule out an IPO or a sale.
SIS has around 35,000 employees, including almost 10,000 in Germany and around 12,500 elsewhere in Europe, mostly in Britain, Italy and Slovakia.