Mexico 3.5 GHz Band Opened to AT&T Mobile Services
Mexico 3.5 GHz Band: CRT Authorizes AT&T Nationwide Mobile Use of 3550–3600 MHz Following Court Ruling
Mexico's Comisión Reguladora de Telecomunicaciones (CRT) has formally incorporated mobile wireless access into nine spectrum concessions held by AT&T Comunicaciones Digitales, S. de R.L. de C.V. in the 3550–3600 MHz segment of the 3.5 GHz band. The decision, adopted unanimously on 11 August 2026 under Plenary Agreement P/CRT/EXT/11082026/095, gives full effect to a final amparo ruling issued by Mexico's Second Collegiate Circuit Court specialized in Economic Competition, Broadcasting and Telecommunications.
The outcome closes a legal dispute that began in 2019 and opens a contiguous 50 MHz TDD block for mobile services across all nine of Mexico's cellular regions — a significant development for 5G network expansion and for manufacturers supplying 3.5 GHz radio and terminal equipment to the Mexican market.
Regulatory Background
The nine concessions were originally granted for wireless access in the 3.5 GHz band and, through a series of corporate transfers and mergers, are now held by AT&T Comunicaciones Digitales. Following a frequency exchange with Teléfonos de México authorized by the former regulator, AT&T's holdings were consolidated into a single contiguous 3550–3600 MHz block effective January 2020.
In September 2019, the Instituto Federal de Telecomunicaciones (IFT) extended the term of the nine concessions but restricted their use to fixed wireless access, expressly excluding mobile service. AT&T challenged this restriction through an amparo lawsuit filed on 6 November 2019.
After the first-instance ruling and the subsequent appeals, the Second Collegiate Court determined that the object of the concessions was indivisible and that the extension should cover both fixed and mobile wireless access. Because the IFT was dissolved in October 2025 and replaced by the CRT, the obligation to comply with the ruling passed to the new regulator, which issued its compliance resolution in August 2026.
For context, Telcel (Radiomóvil Dipsa) obtained mobile authorization for the adjacent 3450–3550 MHz segment in February 2022. The CRT used the consideration paid in that precedent as the reference methodology for calculating AT&T's fee.
Summary of Changes in the Mexico 3.5 GHz Band Resolution
Item | Before (IFT, 2019) | After (CRT, August 2026) |
Authorized service | Wireless access fixed only | Wireless access — fixed and mobile |
Frequency segment | 3550–3600 MHz | 3550–3600 MHz (unchanged) |
Bandwidth | 50 MHz | 50 MHz, contiguous |
Duplex scheme | TDD | TDD |
Coverage | 9 cellular regions | 9 cellular regions (nationwide) |
Concession term | As extended in 2019 | Unchanged — mobile service follows the same term |
Status of mobile service | Not authorized | Authorized on a secondary basis |
Technology | — | Technology-neutral (no specific mobile technology mandated) |
Key points of the resolution:
No new spectrum was assigned. AT&T did not acquire frequencies through an auction; the CRT expanded the services authorized on spectrum AT&T already held.
Technology neutrality. The resolution changes the authorized service rather than approving a particular mobile technology, although the block is well suited to 5G NR deployment.
Consideration fee. The CRT set a total payment of approximately MXN 7.83 million, of which roughly MXN 6.27 million corresponds to Region 9 (Mexico City, State of Mexico, Hidalgo and Morelos). Amounts were calculated using the July 2026 consumer price index and must be updated to the latest INPC at the time of payment.
Conditional effect. AT&T must pay within 30 business days from the day after notification. Payment implies acceptance of the new technical conditions; non-payment leaves the resolution without effect.
Technical Conditions Attached to Mobile Use of the 3.5 GHz Band
Annex I of the resolution replaces and adds conditions in all nine concession titles. Annex II identifies specific protection points in certain regions (this information is classified as reserved in the public version).
1. Frequency arrangement and segmentation The 50 MHz block must be operated in TDD mode following the unpaired frequency arrangement for the band set out in Recommendation ITU-R M.1036.
2. Coexistence with the Fixed Satellite Service (FSS) Mobile service is allocated on a secondary basis in this band, while the Fixed and Fixed-Satellite Services hold primary status. AT&T must:
Not cause harmful interference to, nor claim protection from, primary services.
Respect a maximum power flux density (PFD) limit measured at the input of FSS earth station antennas (referenced to 0 dBi antenna gain), which may not be exceeded beyond a defined percentage of time.
Apply this limit to the aggregate emissions of the network, including user terminals, in both co-channel and adjacent-channel scenarios relative to FSS operations in the extended C-band.
Accept that the CRT may revise the PFD limit, modify station and terminal operating characteristics, or order mitigation measures based on field tests and operational evidence.
Reach technical coordination agreements if new FSS earth stations begin operating in the regions listed in Annex II.
Notably, the CRT's technical opinion removed the exclusion radii that previously prohibited infrastructure around certain earth stations under the fixed-only titles, replacing them with the revised PFD-based protection framework.
3. Harmful interference and national security satellite links If interference occurs, AT&T must follow technical coordination procedures, including suspension of interfering emissions until the CRT confirms the issue is resolved. AT&T must designate a technical contact with decision-making authority to respond immediately to interference incidents particularly those affecting FSS systems used for national security communications under the Mexican satellite system and notify the CRT of this contact within 5 business days of notification.
4. TDD synchronization and coordination Because the band operates in TDD, all fixed and mobile wireless access concessionaires operating in the band must agree among themselves on a synchronization method and frame structure to prevent interference between adjacent blocks. Operators may jointly propose a new synchronization mechanism to the CRT in the future, for example as traffic grows or new entrants join the band.
5. Annual technical reporting During the first quarter of each calendar year, AT&T must submit a detailed technical report including station coordinates, antenna heights, EIRP per transmitter, RSRP/RSSI coverage maps, operating frequencies and channels, and the air-interface technology used.
6. Equipment homologation All telecommunications products, equipment, devices or apparatus that connect to a telecommunications network or use radio spectrum must be homologated before installation and operation, in accordance with the Ley en Materia de Telecomunicaciones y Radiodifusión (LMTR) and the applicable homologation guidelines.
7. Spectrum efficiency and EMF exposure AT&T must meet spectrum efficiency levels set by the CRT and comply with the maximum human exposure limits for non-ionizing RF electromagnetic radiation established in the applicable IFT technical disposition.
What This Means for Manufacturers
The resolution is addressed to AT&T, but its effects reach directly into the equipment supply chain:
Growing demand for 3.5 GHz mobile equipment. With both Telcel (3450–3550 MHz) and now AT&T (3550–3600 MHz) authorized for mobile service, the 3.5 GHz band becomes a core 5G capacity layer in Mexico. Demand for base stations, small cells, CPEs and handsets supporting this range (5G NR band n78) is expected to increase.
Homologation remains mandatory. Every radio product intended for this network infrastructure and terminals must hold valid Mexican homologation before it can be installed or operated. Devices lacking 3.5 GHz coverage in their test reports and certificates may need updated testing or certificate amendments.
Terminal emissions now count toward satellite protection. Because the PFD limit applies to aggregate emissions including user equipment, out-of-band and spurious emission performance of terminals and radios operating near the upper edge of the band becomes commercially relevant to operators.
TDD synchronization support. Base station and small-cell vendors should be prepared to support the frame structure and synchronization method that operators in the band agree on, including GNSS- or network-based timing.
Technology-neutral, but 5G-ready. No specific technology is mandated, so LTE TDD and 5G NR equipment can both be deployed, provided they meet the concession's technical conditions and homologation requirements.
Certification Impact Summary
Area | Impact level | Practical effect for manufacturers |
Mexican homologation (CRT) | High | Mandatory before installation/operation of any 3.5 GHz mobile equipment on the network |
Band coverage in test reports | Medium–High | Products should explicitly cover 3550–3600 MHz (n78) in Mexican test reports and certificates |
Spurious / out-of-band emissions | Medium | Aggregate PFD limit toward FSS earth stations includes terminal emissions |
TDD frame / synchronization | Medium | Infrastructure must support the synchronization scheme agreed by operators in the band |
RF exposure (EMF) | Medium | Network deployments must meet Mexican non-ionizing radiation exposure limits |
New technical standard | None | The resolution does not create a new equipment standard; existing homologation rules apply |
Timeline and Required Actions
Date / Milestone | Event | Required action |
18 Sep 2019 | IFT extends nine concessions for fixed wireless access only | — |
6 Nov 2019 | AT&T files amparo lawsuit | — |
Jan 2020 | 3550–3600 MHz consolidated as a contiguous block after frequency exchange with Telmex | — |
Oct 2025 | IFT dissolved; CRT assumes regulatory functions | — |
Feb–Mar 2026 | Second Collegiate Court ruling becomes final; CRT ordered to comply | — |
11 Aug 2026 | CRT approves resolution P/CRT/EXT/11082026/095 adding mobile service | — |
Notification + 5 business days | Deadline to designate interference-response technical contact | AT&T |
Notification + 30 business days | Deadline to pay ≈ MXN 7.83 million (INPC-updated) | AT&T non-payment voids the resolution |
On payment | New technical conditions take effect in the nine concession titles | AT&T; operators in the band agree on TDD synchronization |
Q1 of each year | Annual technical network report to the CRT | AT&T |
Ongoing | Homologation of all equipment before installation and operation | Manufacturers and importers |
Recommended actions for manufacturers:
Review your Mexico product portfolio for 3.5 GHz (n78) support and confirm that existing homologation certificates cover the 3550–3600 MHz range.
Update test reports and certificates where band coverage is incomplete before supplying equipment to operators deploying in this segment.
Assess emission performance at the upper band edge, given the aggregate PFD protection requirements toward FSS earth stations.
Coordinate with operator customers on the TDD frame structure and synchronization requirements expected for the band.
Monitor CRT publications for any revision of PFD limits, synchronization agreements or updates to homologation guidelines.
Conclusion
The CRT's resolution transforms AT&T's 3550–3600 MHz holdings from a fixed-only asset into a nationwide mobile capacity layer, strengthening competition in Mexico's 5G market. The authorization comes with demanding conditions focused on satellite protection, TDD coordination and network transparency, while the existing homologation framework continues to apply to every device and radio deployed. Manufacturers targeting Mexico should treat this as a signal to verify 3.5 GHz band coverage in their certifications and prepare for increased operator demand in this segment.
