Tamil is a language with phonetic rules which exclude certain words from the Tamil language. One such exclusion is the word Telugu. This word CANNOT be a legal Tamil word and cannot be written using the Tamil script! The closest word, தெலுகு, is read as Teluku (or Teluhu in Sri Lanka).
The phonetic rule in question is that a stop is voiced if and only if it is preceded by its corresponding nasal sound. For example, the letter க (ka) will be voiced and pronounced as ‘ga’ if it is preceded by its nasal, ங, (nga). Otherwise, it will be unvoiced and pronounced as ka.
Hence if we desire to pronounce the last letter as ‘gu’ and not ‘ku’, then we have to insert the corresponding nasal, ng, in front of it. Hence, தெலுங்கு, Telungu is the closest word to Telugu, which satisfies the Tamil phonological rules.
Tamil does not have aspirates nor voiced aspirates. The phonological rules really help in increasing the “distance” between words, thus making it easier to distinguish.