The expected announcement's timing could be delicate, coming after Cisco announced job cuts and after the US presidential debate, in which Trump decried the flow of jobs to Mexico and other countries.
Microsoft will build cloud infrastructure for the two carmakers that can host navigation data and allows drivers to predict gas usage and check on their cars remotely.
Telco, which has no wireless service and has been exploring the sale of its data center business, saw sales fall 0.7 percent last year to $17.9 billion.
The German telco is trying to seize the Internet of Things opportunity in industries like construction and health care, hooking machines to the web so they can work more efficiently.