Preliminary chemistry meetings are being held with agencies this week before a shortlist is drawn up. UKTV is expected to make its agency appointment by the middle of December.
The review was called by Maya Bhose, UKTV's marketing director, who said: "We have enjoyed a very close and positive relationship with PHD over the years, and we rate them highly. But we have a duty to review all our suppliers on a regular basis to ensure we are getting the best service and the best value for money."
UKTV runs nine branded digital channels, predominately on the premium cable and satellite platforms, although UKTV History and UKTV Bright Ideas are available on Freeview.
In audience terms, its most popular channel is UKTV Gold, which shows vintage BBC comedy. However, it has recently seen its dominance of the older, more upmarket sector of the multi-channel audience threatened by the launch of ITV3.