You may have noticed that certain numbers that start with 0, e.g: 017377XXXX or 04326XXXXX will become 1737XXXX and 4326XXXXX. That is because it is a built in Excel function to remove any leading 0 as Excel interprets 0312 as 312 since they are the same value.
If you want to keep the 0 in front of the number, you will have to add a ‘ sign before the number, e.g: ‘017377XXXX or ‘04326XXXXX to keep the zero in-front. This is not an app issue, rather Excel cutting the numbers.