The Analog Devices / Maxim Integrated DS21Q55 is a telecom interface IC. It operates at 3.14V-3.47V and has an operating temperature range of 0°C to 70°C.
The Microchip Technology PM4351-RGI is a telecom interface IC with transceiver functionality. It operates at 3.3V and is housed in a surface-mount 80-QFP package.