For most mortgage borrowers, the first of the month is payment day. This month, however, is a very different story. Millions of borrowers have either lost jobs or income, and are suddenly struggling to make those monthly payments.

Borrowers with government-backed mortgages, through Fannie Mae, Freddie Mac, the FHA or the VA, are entitled to a loan forbearance plan under the administration's economic recovery plan. They can miss up to one year of payments, which will then be added to the back end of their mortgages.

These loans make up 62% of the total market of first lien mortgages, according to the Urban Institute.

The rest are mostly held by banks or private lenders, and a very few are in private-label mortgage-backed bonds. Large banks like Wells Fargo and Chase are also working with borrowers to offer forbearance.

At Caliber Home Loans, which services about 750,000 government-backed mortgages, the phone and internet lines are lighting up.

"Call volumes are up very significantly, they're up about six times," said Sanjiv Das, CEO of Caliber. "We have set up IVR, which is the integrated voice response, which basically allows customers to self-service. On Sunday itself we had 8,000 IVR requests that were people able to get their own forbearance online."

Das headed Citibank Mortgage during the subprime crisis, when millions of borrowers lost their homes to foreclosure.

"Oh goodness, this has been a very abrupt shift, I must say, compared to the last housing crisis," he said.

The housing and mortgage markets are much healthier now than they were then. Homeowners have a record amount of equity, compared with the subprime crisis when home values plummeted and millions of borrowers were underwater on their mortgages, owing more than their homes were worth.