What does mean zhōngxing from ZTE in Chinese? ZTE is the Chinese company that makes, among others, modems, routers, smartphones, etc.
中興 as a single term, does mean "revival, restoration" particularly refers to a period of revival of a declining dynasty.
中興 is mostly a history text book term, when we are talking about a particular period in history. It is never used in contemporary sense. People who were living in a 中興 period would not refer their country's revival as a temporary state
However as a company name in this case, we have to see 中 and 興 as individual characters because China is not in decline. and 中 clearly refers to 中國 (China), not 中期(middle period)
中 stands for: 中國 = China
興 means: "thriving; prosperous; flourishing" as in "興盛" (thrive,flourish)
中興通訊 means "Flourishing China Communication "
Source: ZTE official site
If you cannot read Chinese, you may refer to the following translations in my poor English:
There are two reasons why this company is called [中兴]:
ZTE is combined by two corporations: 中国航天691厂(CASC 691 Factory, a Chinese company) and 兴运 (Xing1 Yun4, a Hong Kong company). take one word from each company, we get[中] and [兴].
Like other users said, 中兴=中国兴盛=China's soaring.