Dialpad supports a number of SIP-based IP desk phones, whether purchased directly from Dialpad or bought from another provider. Included here are just a few examples.
Polycom
Firmware 4.X.X+
VVX Series: 101, 201, 300/310, 301/311, 400/410, 401/411, 500, 501, 600, 601, D60, 1500
Obihai
Firmware 5.1.4.xxx
Versions: 200, 300 (Obi ATA), 1032, 1062