The DP-151 was made by Nokia for the Digital Phone Group. The project was called HD720, rather than a specific codename which Nokia had not started using at the time.
The sister products sold on the NTT DoCoMo network were the NM811 (2GHz version) and NM151(1.5GHz version). They were all launched in 1995 and were extremely successful for the time.
The design of the DP-151 was a variant of the hugely successful
Nokia 2110.
There was an update to the range, the DP-152, NM101 and NM151 which had a slightly updated industrial design and a different style of pull-up antenna - likely based on the
Nokia 2110i. This follow up variant of the phone also had mobile data when connected to a PCMCIA card.