Regarding minutes, how many minutes? My kids basically hog my VoIP "landline" talking to their cousins 50% of the time they're home. (They're actually playing g

Regarding minutes, how many minutes? My kids basically hog my VoIP "landline" talking to their cousins 50% of the time they're home. (They're actually playing games together and using the phone as voice chat). I've been thinking of trying to get a second line for them to hog but didn't want anything with limited minutes.