Frontier Corp., Rochester, NY, has signed an agreement to buy GlobalCenter of Sunnyvale, CA, an Internet, data, and digital-distribution service provider. Frontier company officials say the addition of GlobalCenter?s services to its integrated product offerings will leverage the capabilities of its nationwide fiber-optic network. The new company, to be called Frontier GlobalCenter, will stay in Silicon Valley and retain approximately 240 employees. The all-stock transaction is expected to increase earnings starting in the first half of 1999.