I tried from my PBX but found that calls met with silence. I looked in the debug info and found a very slight difference in the data for a call that worked and one that didn't, but never followed through.
I tried with the Obi202 by putting the URI in a speed dial as such sp2(lenny@sip.itslenny.com) which is the format that works with another sip uri I was testing. It does not return an error, just silence. The other uri I tested with is sp2(music@iptel.org) and it works, so I know I have the format correct. Note that SP2 in my case is configured and in my case,
voip.msHow were you trying to forward them from the Obi?