Please: check out 
https://nl.wikipedia.org/wiki/Telefoonnummer
For example:
'+31 20 1234567	internationale notatie'
In my case at 't Vossenhol in Daarlerveen, +31 546 607103 was good: international +31, regional 546 and local 607103. Why did you split it into 607_103 ?
I know that it is often written like that, but it is not according to what it should in OSM - in my opinion.