Many newer phones can receive NavIC alongside GPS and other systems, but only inside NavIC's coverage area of India and about 1,500 km around it.
When your phone shows your location, it is rarely using GPS alone. Modern chips listen to several satellite systems at once and combine them. Some of them include India's NavIC.
Apple's specification for the iPhone 15 Pro, for example, lists GPS, GLONASS, Galileo, QZSS, BeiDou and NavIC. Your own phone's specification sheet will say whether it supports NavIC.
For years NavIC satellites broadcast only in the L5 and S bands. GPS's main civil signal, the one every phone uses, sits in a different band: L1, at 1575.42 MHz.
ISRO's second-generation NVS satellites add a civil signal on L1. ISRO says the L1 signals widen NavIC's services, and that all new NavIC satellites from 2023 onwards broadcast in L1, L5 and S. NVS-01, the first of them, was launched on 29 May 2023 on GSLV-F12. Mobile network standards have also caught up: ISRO notes that 3GPP's LTE specification includes assisted NavIC.
More satellites in view means a faster, steadier fix, especially in cities and hills where buildings or slopes block part of the sky. NavIC's satellites stay over the Indian region, so they are always somewhere in India's sky.
NavIC also gives India a navigation and timing source under its own control. Outside its service area, though, a phone simply falls back on GPS and the other global systems.
Check the NavIC coverage map: your phone can only use NavIC inside that shaded region. See which NavIC satellites are up
Why does the frequency matter? A receiver's radio front end is tuned to particular bands. A NavIC signal at L5 (1176.45 MHz) is 1575.42 − 1176.45 = 398.97 MHz away from GPS L1, so a receiver tuned only to L1 cannot hear it. Putting a NavIC signal on L1 lets an L1 receiver pick it up.
The receiver then treats NavIC satellites as extra rows in its positioning equations:
R_j = ρ_j + c × b_sys + c × b + errors
When several systems are combined, the receiver must also solve for a small time offset between each system's clock (b_sys), because GPS time and NavIC time are kept separately. So with GPS and NavIC together there are five unknowns (x, y, z, b and one inter-system offset), and five satellites are the minimum; in practice a phone sees far more.
How high does a NavIC geostationary satellite appear? For a ground station at latitude φ and a satellite at longitude difference Δλ, the central angle γ satisfies cos γ = cos φ × cos Δλ, and the elevation is E = arctan((cos γ − 0.1513) / sin γ), where 0.1513 = 6,378 / 42,164. From Delhi (about 28.6° N, 77.2° E) to the satellite slot at 83° E: Δλ = 5.8°, cos γ = 0.878 × 0.995 = 0.874, γ ≈ 29.1°, sin γ ≈ 0.486, so E = arctan((0.874 − 0.151) / 0.486) = arctan(1.49) ≈ 56°. That satellite stands well above the southern horizon all day.
ISRO quotes NavIC SPS position accuracy better than 20 m (2σ) in the primary service area.
The L5 band (1176.45 MHz) and the S-band.
They add a civil signal in the L1 band, at the same 1575.42 MHz frequency as GPS's main civil signal; ISRO says this widens NavIC's services.
No. NavIC serves India and about 1,500 km around it; elsewhere the phone uses global systems like GPS.