steps :-

1. login as admin/reseller.
2. go to Tariff > personalised rates.
3. create a OR by using initial increment. (for ex :- prefix = 55, cost/minute = 0.60 USD, initial increment=0, increment = 60.   It will be apply as per second call charges) 
4. now registered SIP devices.
5. Dial PSTN number by using above prefix.
6. call disconnected after 10 sec and checked call charges in CDRs and observe.

Actual result :- when configured initial increment in personalised rates, then it didn't applied in call charges. 

Expected result :- when configured initial increment in personalised rates,  it should be apply in call charges.

See videos :-