The line, operated by the Canadian Forces Morale and Welfare Services Group, offers trained counsellors who can help soldiers and their families connect with local services, community help and military chaplains.
Separate from existing operational stress injury support and crisis lines, the expanded service comes amid a recent series of suicides among Canadian Forces veterans.
The expansion of the family support line was announced in April of last year and again in October as part of National Family Week. But a general order, obtained by The Canadian Press, shows the operation only came up to full speed within the last two weeks.
National Defence spokeswoman Marie-Helene Brisson says the agency increased the number of positions slowly and made sure processes were in order before advertising it.
She says the resources to increase staff were made possible by reducing management overhead costs.
There have been eight apparent suicides in the military over the last two months, prompting a lot of public attention on the care and services available to soldiers and their families.
A veterans advocate welcomed the arrival of the full service, but expressed concern about what comes after someone gets in touch with the counsellor.
"It's one thing to increase access to a family support line, it's another to ensure the social and mental resources are available in an expedient and timely fashion," said Mike Blais, president of Canadian Veterans Advocacy.
"At this point in time, that is the major question. When people do reach out, is there help available?"
In a fall 2012 report, military ombudsman Pierre Daigle expressed frustration at the "chronic under-manning of the CF mental health" unit. Support to families had improved considerably over the years, said Daigle, but just because programs are expanded doesn't mean they are "sufficient."
"We need adequate resources that can be brought to bear in a timely, efficient manner," said Blais, who added that he doesn't see much improvement in the 18 months since Daigle's report.
Earlier this month, veterans took matters into their own hands and set up their own hotline to help fellow soldiers in crisis. Liberal MP Jim Karygiannis helped them set up a support system where ex-service members volunteer to answer telephone calls.
Since 2002, the federal government has poured nearly $110 million into improving mental health services within the military, including an often quoted $11.4 million announced just prior to the ombudsman's report.
Earlier this month, NDP Leader Tom Mulcair wrote the prime minister and urged him to make military suicides a priority. New Democrats also called for an acceleration of the investigation process for suicides within the military, some of which have been pending for five years.
The toll-free support line for struggling members of the military and their relatives is 1-800-866-4546.