In their submission to the CRTC the bureau stated:
The terms of such roaming agreements—
—that is, what they're charging the other company for their customers to be there in that area—
—are a strategic tool that incumbents can use to protect their market power.
Furthermore, they stated:
In the Bureau's view mobile wireless markets in Canada are characterized by high concentration and very high barriers to entry and expansion.
Later, they say:
Given these factors the Bureau's view is that the incumbent service providers have market power in Canadian retail mobile wireless services.