The Avaya J139 IP phone is a cost-effective communication device for users who require basic voice capabilities in enterprise environments. This IP phone offers high-resolution audio through wideband codec support in both the handset and headset, which reduces listening effort and improves call clarity.

The 2.8-inch colour display with 320 x 240 pixel resolution provides intuitive access to call management functions via four context-sensitive softkeys for operations such as hold, transfer, conference and call forwarding. Four two-colour red/green LED indicators provide visual status information for improved task management.

Hardware features include fixed keys for phone, messages, contacts, history, navigation, headset, speakerphone, volume control and mute. The device supports full duplex speakerphone operation and has in-built volume amplification for hearing assistance, eliminating the need for separate amplified headsets. Network connectivity is provided by dual Gigabit Ethernet ports (10/100/1000 Mbps), with the second port enabling PC connectivity. Power-over-Ethernet Class 1 design supports energy-efficient operation with sleep mode capability.

Communication protocols include SIP support with standard G.711, G.726, G.729A/B, G.722 and Opus codecs. Security features include TLS and SRTP encryption for protected communications. The phone stores current call lists with 100 entries and supports contact lists with 250 entries.

Ergonomic design includes TTD acoustic pairing compatibility and 360-degree visible call notifications. Mounting options include standard two-position desk stand and optional wall mount. This black phone measures approximately 20 cm in height and weighs 850 g, providing reliable voice communication for business environments that require basic telephony functions with improved audio quality and operational simplicity.