Cell towers in Ermont (Val-d'Oise)

Masts stand at 409 Rue Général Leclerc, rue du Pr Calmette, Stade Renoir, square des Grands Arbres, 15 rue Louis Armant and 72 Bis Rue de la République.

Over the past 12 months ANFR recorded 15 new systems here. ANFR has approved one new site that is not live yet, plus additions on 6 existing masts. New: Bouygues Telecom (4G and 5G) at avenue Président Georges Pompidou. 14 Bouygues Telecom 5G transmitters are listed as technically operational — installed, but not yet declared commercially in service.

Systems from 2004 are still on the register. Local 5G started with Bouygues Telecom in November 2020; Free Mobile followed in December 2020, SFR followed in October 2021. 2017 was the busiest year, with 22 new systems, most of them 4G.

On 3.5 GHz, the fastest 5G band: Bouygues Telecom on all 7 masts, Free Mobile on all 5 masts, SFR on 5 of its 6 masts and Orange on all 3 masts.

Most antennas sit on rooftops (15 of 18), so heights stay modest; the tallest support is 36 m.

Nearby, Eaubonne (2 km to the north-east) has only 13 masts.

5 supports carry only SFR.

Among the 43 Val-d'Oise towns with at least five masts, Ermont ranks 9th by mast count.

At 4 km² with 29,489 residents, the commune is dense enough that most antennas sit on rooftops rather than pylons. It is part of the CA Val Parisis intercommunal grouping.

Most of the town's 18 masts are buildings (15).

Figures above cover installations declared to ANFR as in service or technically operational, as of October 2026; approved projects are not counted.