Check if call is coming from a fixed or mobile phone with tasker
Depending on the set up of your profile use the following: 

In the Task step add the If statement: %CNUM ~ 9*/8*
This means that the step will be executed only for number starting with 9 or 8.

Alternatively, set up the whole profile to only activate if the caller's number starts with 8 or 9.
In Event (like Incoming Call) settings: Caller (normally says Optional) specify 9*/8*
This means the profile will be only activated if the number starts with 9 or 8.

Hopefully, this will work for you.

For more info see: http://tasker.dinglisch.net/userguide/en/matching.html