http://www.mountainwireless.com/sid/sid1.shtml
SID is location based. Probably why you're roaming.
Double check all your other EPST settings against what the opening poster has.
PRL version is one that might be giving you problems too.
After that, try a *228.
That mountainwireless page was ugly so i made it a little easier to search for a SID. Not the greatest, but better than nothing. I wrote a quick
vb app to parse the original list. 0-9999 listed. I had it searching by state, but there's too many without a state listed in the original.
http://ppckitchen.org/sid.html