T-Mobile and Verizon are likely to be mismatched rivals once the FCC’s 600 MHz incentive auctions roll around next year but for now the carriers are teaming up to advocate a band plan.

In a new FCC filing, T-Mobile and Verizon both pushed for the Commission to adopt a “down from channel 51” for the incentive auctions. The two carriers accentuate four points to their argued approach: it will maximize paired spectrum, allow for cost-effective and timely deployment of network equipment and devices, promote interoperability through a single 3GPP band class for all 600 MHz paired blocks and allow for extra downlink from any non-paired spectrum not needed to prevent interference.

T-Mobile and Verizon suggest a 35x35 MHZ Frequency Division Duplexing pairing that will only require a single band class. That single band class will keep costs down for infrastructure vendors and OEMs, savings that will hopefully trickle down to end-users. But the supplemental downlink that the carriers are arguing for stands as a sticking point for Dish Network.

In an FCC filing from August, Dish argued that allowing for supplemental downlink could actually work against the adoption of a common 3GPP band. The satellite provider also claims that many smaller carriers lack the low-band spectrum to efficiently use supplemental downlink and therefore would be less likely to participate in a 600 MHz auction if the band plan allocates for it.

Despite the differences of opinion on supplemental downlink, there appears to be a large amount of industry support for a “down from channel 51” plan.

FCC Commissioner Ajit Pai commented in July that the FCC’s goal has to be figuring out how much spectrum to pair above channel 37 and stressed the need to avoid the interference that has hurt the lower 700 MHz A Block spectrum the FCC previously auctioned off.