We have a colleague working over in Saudi Arabia. The standard BT call tariff to her landline is £1.45 per minute, plus a 23 pence call setup charge. Fortunately with are using Google GSuite and it's associated Google Voice. The cost per minute is £0.07 and no call set up charge. Our last call was 62 minutes long and cost us £4.54. If we'd used BT it would have been: £90.22 for the same duration.
If you need to make good sound quality International business calls, look no further than Google Voice. If you are calling the USA, the rates are even better, the calls are free. An incoming direct dial phone line is about £5 a month. The Google software allows you to administer call services for the team and as an option you can have the usual PABX facilities.