The word is a logical combination of two smaller words: 电话 (diànhuà), meaning “electric speech” or “telephone,” and 号码 (hàomǎ), meaning “number/code.” Put together, 电话号码 (diànhuà hàomǎ) literally means “telephone's number-code,” or simply, “phone number.”
In China, a phone number is more than just a string of digits; it's often imbued with cultural meaning related to numerology and homophones (words that sound alike).
While 电话号码 (diànhuà hàomǎ) is the correct full term, its usage varies by context.