Though you have not mentioned I assume the following.
- He is calling (FaceTime) through his Apple ID
- You are calling (FaceTime) on his Mobile Number.
Status: He has still not activated FaceTime for his Mobile Number.
![](https://support.apple.com/library/content/dam/edam/applecare/images/en_US/mac_apps/itunes/divider.png)
To activate iMessage and FaceTime using a Phone number
First, check to know whether you have an SMS plan enabled at least for One SMS*** with your carrier. Contact your Carrier (Cellular Service Provider) the agency that issued the SIM to you
If your iPhone is used with a carrier not found in the wireless carrier articles, make sure you can send and receive international SMS. (One SMS*** Only)
If you can't turn on or sign in to iMessage or FaceTime - Apple ...
*** You may not have an SMS plan enabled by your carrier for the SIM that you use on your device. Apple Inc does not provide SMS services.
![](https://support.apple.com/library/content/dam/edam/applecare/images/en_US/mac_apps/itunes/divider.png)