Excel often strips plus signs, leading zeros, or country codes when handling phone numbers. These formatting changes seem minor but cause mobile and email clients to misread numbers. vCard files store phone numbers exactly as defined, including international formats. That’s why converting Excel contacts into VCF is more reliable. When dealing with international contact lists, I’ve found Softaken Excel to vCard Converter useful because it preserves number formatting during export, preventing errors on Android, iPhone, and email clients.