C Spire Wireless, the Tier 2 carrier that essentially kickstarted the current rollover data frenzy, announced it will extend its own program to cover shared data family plans.

Starting Jan. 19, C Spire customers on 10GB, 15GB and 30GB shared data plans will start seeing their unused data roll over to the next month. The carrier says rollover data can be accumulated, shared and used among all individuals for up to twice the plans’ included monthly data amount.

The updates to C Spire’s offer will hit before AT&T’s newly announced rollover data offer for its Mobile Share plans. AT&T’s plans, unlike the offering from C Spire and T-Mobile’s new Data Stash, don’t allow rollover data to be accumulated. Only unused plan data can be carried over month-to-month.

C Spire’s rollover data plan kicked off in November with single-line plans and was followed shortly after by T-Mobile’s Data Stash, part of the company’s latest Uncarrier announcement.

T-Mobile’s Data Stash garnered mixed receptions from analysts, with some noting it could reduce churn for T-Mobile while others colored it as a poor substitute for giving subscribers more control over their data or money back for unused data.