The full answer
Not simply because the front of the package says Halal.
Sausages can contain meat from multiple sources, casings, spices, flavorings and other ingredients.
For processed products, both the meat source and manufacturing process should be verified.
Answers in the Halal Knowledge Center reflect the standards followed by Halal Monitoring Services (HMS), which operates as part of the Shariah Board of America. HMS certifies only what it checks.