Dialer not setting Preferred Line for custom TSP

Dialer not setting Preferred Line for custom TSP

I was trying to build a custom TSP. The problem is, it is not showing in
the Line drop down of dialer. If I use the 'Connect Using...' menu item,
it gets listed in the drop down!
Also, after I select my tsp from the Line drop down, the 'Preferred Line'
key in registry is not getting updated, (resets to 0). What am I missing.
I was wondering about the significance of the number shown in 'Preferred
Line' for other tsp. Where did it came from? Is it something I return
during 'TSPI_providerInit' or something like that?
Any idea is welcome.