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LTE Cat 4 Cell Modem Card

The LTE Cat 4 Cell Modem Card is a long-running community project to create a cellular LTE modem expansion card for Framework laptops. Originally proposed by engineer Tim Taylor in October 2021, the project has gone through multiple design iterations by different community members and companies, with the most recent active effort being an ultra-compact open-source design by Filip Stedronsky (Filip_S) based on the Quectel EG95 modem module12.

Framework itself highlighted the LTE expansion card concept in a January 2022 blog post as an example of the community-driven ecosystem enabled by the Expansion Card Developer Program3.

Tim Taylor's Original Design (2021)​

Engineer Tim Taylor posted the first LTE Cat 4 modem expansion card design in October 2021. The design featured1:

  • Nano SIM card slot — hidden below the card rail when fully inserted
  • 2× MMCX connectors — for primary and diversity antennas (external, as integrated antennas could not fit)
  • Transmit LED — between the antenna connectors
  • Cat 4 speeds — 150 Mbps downlink / 50 Mbps uplink
  • Carrier support: Verizon (LTE B2, B4, B13; UMTS B2, B5) and AT&T (LTE B2, B4, B5, B17; UMTS B2, B5)

Design challenges included finding a modem module small enough to fit the expansion card housing and routing antenna connections. The antenna connectors required an extra 0.5 mm of length beyond the standard expansion card dimensions. Framework co-founder Nrp suggested using a 0.1 mm mylar sticker for the card lid, similar to what Framework uses internally1.

The project status at the time of posting was schematic and layout complete (100%), documentation at 25%, with no prototype constructed or tested1.

Liberated Embedded Systems — openCom LTE (2023–2024)​

In June 2023, Jacob Eva of Liberated Embedded Systems Ltd (UK) announced the openCom LTE, a fully open-source LTE expansion card based on the Quectel EG95 module45. The design was certified by the Open Source Hardware Association (OSHWA) as UK0000506.

Design Features​

FeatureDetails
ModemQuectel EG95 (LGA package)
Antenna connectors2× SMA (primary + diversity) + 1× U.FL (GPS)
SIM slotNano SIM push-push holder
SpeedsLTE Cat 4 (150 Mbps down / 50 Mbps up)
Design toolKiCad
LicenseCC BY-SA 4.0
OSHWA certificationUK000050 (October 2023)

The card exceeded standard expansion card dimensions by a couple of centimeters due to the SMA connectors, similar in size to Framework's Ethernet Expansion Card4. Design files including schematics, PCB layout, BOM, and OpenSCAD enclosure were published on the company's Git server5.

The openCom LTE was briefly sold at approximately £145, but Liberated Embedded Systems cancelled the project in late 2024 citing viability concerns around demand, cost, and manufacturing challenges. The company pivoted to LoRa radio products (openCom XL) and no longer produces Framework expansion cards7.

Josh Cook's LTE Card (2024)​

Community member Josh Cook (i2clabs, Australia) began selling an LTE expansion card in early 2024 for $100 USD (later listed at $160 on the i2clabs store)89. The card used Quectel EG95 variants — EG95-AUX, EG95-NAX, and EG95-EX — selected by destination country, with internal antennas and a form factor similar to the Ethernet Expansion Card8.

Delivery Issues

Multiple customers reported paying for cards that were never delivered. Josh Cook became inactive on the Framework Community in December 2024 and did not respond to messages. Several customers successfully obtained chargebacks via their banks or PayPal, while others were unable to dispute charges after the dispute window expired. A community moderator intervened to remove personal attacks but confirmed the validity of complaints10.

Zokhoi's Design (2025)​

Community member zokhoi created an open-source cellular expansion card PCB design published on GitHub. The design uses MHF-1 connectors for LTE main, diversity, and GNSS antennas and is compatible with Quectel modules sharing the BG96 pinout, including the EG912U-GL and EG95-EX. The PCB measures 26 mm × 45 mm with 4-layer impedance-controlled construction11.

Filip Stedronsky's Compact Design (2025–Present)​

The most recent and actively developed effort is by Filip Stedronsky (Filip_S), who created an ultra-compact open-source LTE expansion card design based on the Quectel EG95212.

Design​

  • Quectel EG95 modem in two regional variants: EG95-EX (Europe) and EG95-NAX (North America)12
  • Extremely compact PCB — sticks out only ~5 mm beyond the expansion slot, plus ~2.5 mm for case walls12
  • Nano SIM support
  • GNSS (GPS) supported with the -X modem variants, using a compact FPC antenna
  • MHF4 (IPEX) antenna connectors for main and diversity LTE antennas
  • Open-source — design files on Codeberg under CERN OHL license2
  • 4-layer PCB, 0.8 mm thick, impedance-controlled for JLCPCB's JLC04081H-7628 stackup2

Prototype Testing​

The first working prototype was assembled by JLCPCB in May 2025 and achieved approximately 30 Mbps down / 20 Mbps up with compact FPC antennas, comparable to a Cat 4 USB dongle at the same location12. On strong signal (outdoor, line-of-sight to cell tower), speeds reached up to 60/45 Mbps. On weaker indoor signals, performance dropped to as low as 15/0.25 Mbps12.

The EG95 module runs hot, reaching 62°C as reported by the module's internal temperature sensor (AT+QTEMP command)12.

Antenna Challenges​

Antenna design and placement emerged as the primary performance bottleneck. Experiments showed12:

Antenna PlacementApproximate Download Speed
Free air (optimal baseline)~35 Mbps
Taped to back of lid1–2 Mbps
Under bottom bezel4–5 Mbps
Over bottom bezel (drilled routing hole)15–25 Mbps

The best practical solution involved drilling a small hole through the expansion card bay to route an antenna cable to the bottom bezel area near the Wi-Fi antennas. This makes the card semi-permanent (not easily hot-swappable) but significantly improves reception12.

Community member FelixL is working on a 3D-printed case design in Onshape12.

Cost Estimates​

For a group order manufactured at JLCPCB (as of May 2025)12:

QuantityEffective Price Per Unit
2 (minimum)~$340
5~$103
10~$85
15~$80

MicroSD Variant​

Filip_S also designed an experimental variant that adds a microSD card reader (UHS-I, GL3224 chipset) using the unused USB3 SuperSpeed lanes through a 4-port USB hub IC. This requires a 6-layer PCB and is available in the microsd git branch12.

Thermal and Mechanical Considerations​

IssueDetails
Thermal managementEG95 reaches 62°C; orienting modem-side down or using a metal case helps but makes lap use uncomfortable12
USB-C connector fragilityThe connector broke off a prototype during unprotected use; epoxy reinforcement recommended12
No ESD/surge protectionThe compact design does not include TVS diodes on the antenna lines2
No regulatory certificationCommunity-built cards lack FCC/CE certification for intentional radiators12

Regional Variants​

The Quectel EG95 is available in regional variants with different band support13:

VariantPrimary RegionGNSS
EG95-EXEuropeYes
EG95-EEuropeNo
EG95-NAXNorth AmericaYes
EG95-NANorth AmericaNo
EG95-AUXAustraliaNo
EG95-JPJapanNo

There is no single global variant; users must select the appropriate module for their region and verify band compatibility with their carrier13.

Linux Compatibility​

The Quectel EG95 is supported by the Linux kernel (version 4.4+) via the option USB serial driver and the qmi_wwan net driver (USB ID 2c7c:0195)14. The manufacturer guarantees Linux and Android compatibility13.

Footnotes​

  1. LTE Cat 4 Cell Modem Card — Framework Community (Tim_Taylor, October 2021) ↩ ↩2 ↩3 ↩4

  2. regnarg/framework-eg95 — Codeberg (Filip Stedronsky, 2025) ↩ ↩2 ↩3 ↩4 ↩5 ↩6

  3. Open Sourcing our Firmware — Framework Blog (January 2022) ↩

  4. LTE Cat 4 Cell Modem Card — Liberated Systems announcement (post #88) — Framework Community (Jacob_Eva_LES, June 2023) ↩ ↩2

  5. openCom LTE Design Files — Liberated Embedded Systems Git ↩ ↩2 ↩3

  6. openCom LTE — OSHWA Certification UK000050 — OSHWA (October 2023) ↩

  7. Liberated Embedded Systems Newsletters — Liberated Embedded Systems ↩

  8. LTE Cat 4 Cell Modem Card — Josh Cook announcement (post #183) — Framework Community (Josh_Cook, February 2024) ↩ ↩2

  9. LTE Expansion Card — i2clabs Store — i2clabs ↩

  10. LTE Cat 4 Cell Modem Card — delivery complaints (posts #304–309) — Framework Community (December 2024 – February 2025) ↩

  11. Zokhoi/framework-cellular-card — GitHub (2025) ↩ ↩2

  12. LTE Cat 4 Cell Modem Card — Filip_S compact design (posts #333–393) — Framework Community (May–June 2025) ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8 ↩9 ↩10 ↩11 ↩12 ↩13 ↩14

  13. LTE EG95 Series — Quectel ↩ ↩2 ↩3

  14. Quectel Wireless Solutions EG95 LTE modem — Linux Hardware Database — linux-hardware.org ↩

  15. FrameworkComputer/ExpansionCards — GitHub ↩