Grandstream GXV3275



First, I thank you, that there is such a forum.

I have a Grandstream GXV3275 phone. I linked the phone to my Google Account. Here all contacts with pictures etc. are imported cleanly.

But here is my problem:
With calls no name appears in the display, but only the call number.
And for dialed numbers is synonymous only the phone number in the call list and no name.

My contact phone numbers are all formatted as follows: +49 171 1234567

I really hope that a professional can help me.