Eddie Hearn has claimed Deontay Wilder's (40-0, 39 KOs) camp are refusing to respond to his emails over a potential fight against Anthony Joshua, joking that they use "carrier pigeons or smoke signals" instead.
Joshua (21-0, 20 KOs), who Hearn represents via Matchroom, is scheduled to defend his titles on April 13 at Wembley after fighting Russian Alexander Povetkin (34-1, 24 KOs) on Saturday.
The unbeaten Wilder has been earmarked as a potential opponent, but Hearn says he is yet to receive a response from the American's camp in his attempts to set up the clash.
"If there's even a chance that an undisputed title fight could happen in April, you've got to at least talk about it. Maybe they don't use emails - maybe Shelly [Finkel] uses carrier pigeons or smoke signals. I'm going to strap a note to a pigeon's leg and send it to New York," Hearn told Sky Sports.
"It's not a case of saying they're concentrating on Fury. It's the promoters' job to plan ahead. It's frustrating because there's limited time to make the fight. People must be realising that they don't want the fight because, if they did, why haven't they replied?"
Joshua's fellow Briton Dillian Whyte stands next in line should Hearn fail to reach an agreement with Wilder, and Hearn admitted that at this stage, an all British affair seems the likelier of the two outcomes.
"At the moment [Whyte is the frontrunner], yes," explained Hearn. "[Whyte] is first going to fight in December. We are negotiating, talking for December 22 at The O2."