（单词翻译:单击）
| 中文 | 英文 | 缩写 |
| 恶化信号 | degraded signal | |
| 恶意呼叫 | malicious call | |
| 恶意呼叫定位信号/恶意呼叫识别信号 | Malicious Call Identification signal | MCI |
| 恶意呼叫追踪 | MALicious Call Tracing | MALCT |
| 耳机 | earphone | |
| 二/四线转换电路 | hybrid circuit (2-wire to 4-wire conversion) | |
| 二叉树 | binary tree | |
| 二次拨号音 | secondary dial tone | |
| 二次电源 | secondary power supply | |
| 二次群 | secondary group | |
| 二次群光传输 | optical transmission of secondary group signal | |
| 二次失效 | secondary failure | |
| 二次数字复用器 | secondary digital multiplexer | |
| 二分查找 | dichotomizing search | |
| 二级保护 | secondary protection | |
| 二级时钟 | stratum 2 clock | |
| 二进制 | binary system | |
| 二进制编码的十进制数加法/BCD数加法 | addition of BCD number | |
| 二进制数加法 | addition of binary number | |
| 二进制数字 | binary digit | bit |
| 二进制同步通信 | Binary Synchronous Communication | BSC |
| 二进制同步协议 | BinarY SYNChronous protocol | BYSYNC |
| 二进制文件传输 | Binary File Transfer | BFT |
| 二进制循环（反射）码/格雷码 | cyclic binary code | |
| 二进制指数退让算法 | binary exponential backoff | |
| 二类传真机（频带压缩/3 min传送一页A4文件） | group 2 facsimile apparatus | G2 |
| 二-十进制/二进制编码十进制数 | Binary-Coded Decimal | BCD |
| 二维 | 2D=two dimensional | |
| 二纤复用段共享保护环 | two-fiber MS shared protection ring | |
| 二纤通道保护环 | two-fiber path protection ring | |
| 二纤自愈环 | two-fiber self-healing ring | |
| 二线/四线转换器 | 2w/4w converter | |
| 二线模拟接口 | 2-wire analogue interface | |
| 二相相移键控 | Binary Phase Shift Keying | BPSK |
| 二义性/多义性/模糊/含糊 | ambiguity | |
| 二元的/二态的/二进制的 | binary | |
| 发电机组 | electric generator set | |
| 发电站 | power station | |
| 发端长话局 | originating toll exchange | |
| 发端端局 | originating local exchange | |
| 发端国际局 | originating international exchange | |
| 发端呼叫/去话筛选 | originating call screening | |
| 发端局 | origination exchange | |
| 发端口 | transmit port | |
| 发端业务/发话话务量 | originating traffic | |
| 发方 | originating party | |
| 发方向 | transmit direction | |
| 发光二极管 | Light Emitting Diode | LED |
| 发话占用数 | number of originating seizures | |
| 发货 | product shipment/delivery/consignment | |
| 发码器 | code sender | |
| 发起呼叫/始发呼叫 | originating call | |
| 发射 | TransMiT | XMT |
| 发射功率跟踪环路 | Transmission Power Track Loop | TPTL |
| 发射关 | Transmit Off | X-Off |
| 发射机/送话器/发送机 | Transmitter | TX |
| 发射机眼图屏蔽 | transmitter eye pattern mask | |
| 发射基带交换 | Transmitter Base Band eXchange | TBBX |
| 发射极化分集 | transmit polarity diversity | |
| 发射-接收装置 | transmit-receive unit | |
| 发射开 | Transmit On | X-On |
| 发收串音 | go-to-return crosstalk | |
| 发送光功率比 | transmitting optical power ratio | |
| 发送母线 | Send HighWay | SHW |
| 发送特殊信号音信号 | Send-Special-Information tone signal | SSI |
| 发送信号眼图 | transmit signal eye pattern | |
| 发信/收信机 | TRansmitter & Receiver | TRX |
