T-calls at yards are done for a number of reasons
1. another driver may have a family emergency and that load gets him close to house, through the house or to the load to get to the house
2. dispatcher sees something coming your way to get you to a good area of freight
3. Scheduled maint on tractor or trailer
4. No freight in destination city and doesn't want you sitting
5. Or just wants to sit you someplace civilized instead of a dusthole..they have good strip clubs in irving/dallas/ft worth areas...
6. you asked to go to a cowboys game a couple of months ago and since forgot you asked and the dispatcher doesn't know that football season is over.