Two Greek characters run inside and telephone a complaint (9)

'a complaint' is the definition.
(murmuring is a kind of complaint)

'two greek characters run inside and telephone' is the wordplay.
I cannot really see how this works, but
'greek' could be 'g' (philological abbreviation) and 'g' is found in the answer.
'run' could be 'r' (cricket abbreviation) and 'r' is present in the answer.
'inside' could be 'in' and 'in' is found within the answer.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?