QBZappy,
Only the OBi device owner allows which numbers to be the COT, as a result, other telephone numbers would not have this service.
I agree with you that this feature will not give any benefit in some place, for instance in Hong Kong. However when the OBi110 device is installed in some countries, for instance Mainland China with a subscription of the "E9" plan from China Telecom, you will be given a fixed PSTN line (denoted by PSTN1) and a mobile phone (denoted by Cell1). Calls between PSTN1 and Cell1 is free within the city. In order to let you undertand the whole situation, I would like to give you different ways of making/receive calls between PSTN1 and Cell1.
1) Supposed PSTN1 is installed in Shenzhen (southern part of Mainland China)
2) PSTN1 calls Cell1 for free no matter the location of Cell1 (all over Mainland China)
3) If Cell1 in Shenzhen calls PSTN1 for free.
4) If Cell1 in other cities (e.g. Beijng) calls PSTN1, certain amount of telephone charge will be imposed
With the new feature, the charge in 4) will be eliminated since PSTN1 will call back Cell1 after Cell1 hangs up.
YH