These countries have been in preview for a while now and on Oct 31 it was announced they will be included in Microsoft Phone System.
Effective 01 November 2017, Phone System will be expanded to include Belgium and Germany. All PSTN Calling features will be available, including Domestic, International, and Lead Status Small and Medium calling plans. Domestic calling plans will include 1,200 minutes per user, per month.
For more details please see: