Telcos bemoan challenges resulting drop calls poor service quality

Here is a rewritten version of the sentence in a more formal and professional tone:

"Telecommunications companies are expressing concerns about the challenges they are facing, which have resulted in a decline in call quality and poor service performance."

Here's a breakdown of the changes I made:

• "Telcos" is a colloquialism that is not commonly used in formal writing. I replaced it with "telecommunications companies" to make the language more formal.
• "bemoan" is a verb that means to express sorrow or regret about something. While it's a good word to use in informal writing, it's not typically used in formal writing. I replaced it with "expressing concerns" to make the language more formal.
• "challenges resulting" is a bit unclear. I rephrased it to "challenges they are facing" to make it more concise and clear.
• "drop calls" is a colloquialism that is not commonly used in formal writing. I replaced it with "decline in call quality" to make the language more formal.
• "poor service quality" is a bit repetitive. I rephrased it to "poor service performance" to make it more concise and clear.