"Her phone number" 的英文表达是 "her telephone number"。
“telephone” 来源于希腊语 "tele"，意为 "far"，和 "phone"，意为 "voice"，组合在一起就是远程传递声音的设备。
例句：
Can you give me her telephone number? (你能告诉我她的电话号码吗?)
I lost her telephone number, do you have it? (我把她的电话号码丢了，你有吗?)
Can you call her on the telephone? (你能给她打电话吗?)