WAN Carrier Services - Referral Programs

A number of "Master Agent" companies for major telecom carriers have been asking me sign up with their referral programs, which would pay me residual commissions monthly, regardless of which specific carrier I recommend to my clients. Is this an acceptable business practice for a WAN consultant? Or is it OK since the compensation is the same, irrespective of the actual carrier I recommend/my client ends up purchasing? Does anyone else have comment on this?