Taco Bell announced in its conference call with investors this week that the chain will soon offer delivery nationwide via Grubhub. Dunkin’ is using Grubhub as well in a test to see if the relationship works for them. The choice of outsourcing delivery to third-party providers instead of building the capability in-house is a tough decision for restaurant chains. While it is tempting to forgo the hassles, forking over a piece of every transaction can seriously erode profits in an already tight-margin business.