Cignal Infrastructure UK applied to build on the grass verge outside Rockingham Junior and Infants on Roughwood Road.
The development would comprise a monopole supporting six antennas, plus three equipment cabinets.
There were 11 objections, including from the school – which also suspected that the consultation period was held during the holidays to minimise the number of objections.
Cignal’s planning papers said: “There is a specific requirement for an installation at Roughwood Road to ensure that the latest high quality 3G and 4G service provision is provided in this area of the city.
“The proposed column will also ensure that new 5G coverage can also be provided at this location.”
But an RMBC spokesperson said: “The council considers that the proposed telecommunications mast by virtue of its siting in a prominent elevated position and open character setting would appear unduly dominant and incongruous in the streetscene.”