Finally Skype for Business PSTN calling is available (in Preview) in The Netherlands and Ireland! PSTN calling is an add-on telephone service that, when combined with Skype for Business Cloud PBX, can become your phone system. PSTN calling provides the people in your business with primary phone number, and lets them make and receive phone calls outside your organization. As described on this page. PSTN calling is currently available in France, Puerto Rico, Spain, United Kingdom and United States.
Microsoft now introduced this add-on in Preview to The Netherlands and Ireland as you can find on the Skype Preview website. There are some requirements before you can join the Preview as stated below, like a minimum of 50 users using PSTN Calling with their Office 365 number.
When PSTN Calling will be General Available is unknown at this moment, but will problably GA in a few months.
More information about PSTN Calling for users from The Netherlands and Ireland is found on the Skype Preview website.