Actually, it is working now- sort of. Probably the mistake was that something happened to the copied and pasted string during the process. thanks.
Which does not mean that I am out of the woods because I stiil have one way audio on Obi 202 not only on Localphone, but also on the two GV accounts. I e-mailed the Obi customer service and hope that they come with some briliant idea. Nothing has changed, the gateway is in DMZ mode and the Obi 100 works without problems.