Following his playing career, Phillips returned to his alma mater UTEP, where he spent one season as a student assistant.
In 2005, the Buffaloes went 10–2 and won the Lone Star Conference with an 8–1 mark with NCAA Division II's top-ranked passing offense.
Phillips helped guide the development of quarterback Dalton Bell, who was a finalist for the Harlon Hill Trophy.
Working together for the first time, the coaches Phillips helped the Cowboys to win NFC East titles in 2007 and 2009.
With the Redskins, Phillips worked with notable tight ends like Vernon Davis and Jordan Reed, the latter of whom made the Pro Bowl following the 2016 season.
In 2021, Phillips added the title of pass game coordinator in addition to his role as tight ends coach.
[18] On December 8, 2023, Philips was arrested in Minneapolis at approximately 9:45 PM CST on suspicion of drunken driving after showing signs of impairment during a routine traffic stop for speeding, with his blood alcohol content later revealed to be 0.10.