These settings should speed up outbound and incoming calls and generally make your OBi more compatible with British phone systems:
Physical Interfaces > LINE Port > LINE Port > DigitMap:
([2-9]xxxxxxS0|0[1-9]xxxxxxxxxS0|xx.S4)
Assumes that local numbers are seven digits. May need adjusting to your local format.
Physical Interfaces > LINE Port > LINE Port > RingDelay: 0
Physical Interfaces > LINE Port > LINE Port > RingProfile: B
Physical Interfaces > LINE Port > LINE Port > DialDigitOnTime: 80
Physical Interfaces > LINE Port > LINE Port > DialDigitOffTime: 80
Physical Interfaces > LINE Port > PSTN Disconnect Detection > DetectFarEndLongSilence: uncheck
Physical Interfaces > LINE Port > Port Settings > ACImpedance: 370+(620||310nF)
Physical Interfaces > LINE Port > Port Settings > CallerIDDetectMethod: FSK(V.23)
Physical Interfaces > PHONE Port > Ringer > RingFrequency: 25
Physical Interfaces > PHONE Port > Port Settings > Impedance: 320+(1050||230nF)
Physical Interfaces > PHONE Port > Port Settings > CallerIDMethod: FSK(V.23)
Physical Interfaces > PHONE Port > Port Settings > CallerIDTrigger: Before First Ring
Let's hope that it still works after that many changes