Was the content of standard mobile text messages ever stored and retained on servers in the UK or the US where either of the government had the ability to scan and read them at their leisure? Thank you

Was there ever a situation where traditional mobile phone text messages were ever stored on servers and kept for a period of time where the US or UK governments had the ability to search and read anybody's messages whenever they saw fit to do so?

I know that the "metadata" has always been available to them but what about the actual "written contents" and how does this stand currently does anybody know? Thanks

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