I believe there is a better solution to this question, but it is quite technically involved.
It requires knowledge and implementation of VOIP/SIP technology.
So basically you can use any country's local/landline number , which is very nice for your clients , and this number routes through the internet to your SIP account which could be (any number of) any thing with an IP address; physical phone on your desk, softphone app on your mobile, etc.
You can have a very nice coverage and availability on many different numbers all converging in your pocket smartphone. Dialing out using the same called ID should also be︀ possible. With this setup the cost of calls should be way cheaper than anything else︁ on the planet.