worth a bugreport. If you have export .vcf from the old phone still around, the full vcard entry (obfuscated with other numbers etc) from begin: to end: would help to file the bug
BEGIN:VCARD
VERSION:4.0
PRODID:+//IDN bitfire.at/..
FN:Firstname Lastname
N: Lastname;Firstname;;;
TEL;TYPE=cell:+41 123 456
END:VCARD