```
Phone number    Provider    Duration (min)
1001            Fastcom         2
1002            Fastcom         1
1004            Mobilecom       4
1008            Telecom         5
1001            Fastcom         3
1001            Fastcom         2
1003            Telecom         3
1004            Mobilecom       2
1008            Telecom         6
1002            Fastcom         1

```

I want to use one formula to get the sum of the duration of calls whose service provider is the provider for the phone number 1001. I hope this revised version is clearer than the previous one. Again, thanks to all who paid attention.