Could You Still Build the Adafruit FONA 808 Today?
Could you still build the Adafruit FONA 808 today?
SIMCom put the SIM808, the cellular module on the Adafruit FONA 808, on end-of-life notice in December 2021, citing a power amplifier that had already reached end of life at its chipset vendor. The board cannot be built as designed: that notice closed the purchase window on 30 April 2022 and names no successor for the SIM808. Three of the ten audited BOM lines returned no authorized distributor listing at all, and all three are connectors. Each line was read from the public schematic and checked against public manufacturer and distributor status.
The three numbers
Three numbers carry the whole audit: ten BOM lines resolve to one manufacturer’s orderable, and three of them returned no authorized listing; zero successors are named for this radio in its own end-of-life notice; and two clocks run against this board, issued three weeks apart, with unrelated causes and deadlines more than a decade apart.
BOM lines audited
Each resolves to one maker’s orderable. Five Active, one NRND, one EOL, and three returned no authorized distributor listing on the audit date. All three are connectors.
Named successors
Alternative part numbers for this radio in its own EOL notice. Every other module type the notice lists carries at least one; the SIM808 row is empty.
Clocks, three weeks apart
The UK 2G/3G sunset joint statement (8 Dec 2021, horizon 2033) and SIMCom’s EOL notice (29 Dec 2021, window closed 30 Apr 2022), with unrelated causes.
The ledger · 10 lines
| # | Desig | Component | Role | Maker | Source | Status |
|---|
Tap any flagged row to open its finding; use the filter to isolate a status. A line is audited when it resolves to one manufacturer’s orderable part number, whatever the part does. Ten lines meet that test, including three connectors and a switch. Parts bought from several makers interchangeably (standard passives, 1N4148 diodes, LEDs by colour, 0.1″ headers, JST PH and uFL) are bucketed, not scored. The KMR2 switch is named as a series; a rebuild picks a specific orderable and confirms actuator height and force.
The same ten lines, on the board they came off. Every footprint and silkscreen label below is parsed from Adafruit’s published EagleCAD board file, so each part sits where the manufacturer placed it.
The keystone & the sourcing gap
The SIM808 holds both the GSM and GPS radios and has no second source in the schematic. SIMCom’s notice of 29 December 2021 set a last order date of 30 April 2022 and last delivery of 31 May 2022, and the “P/Ns of Alternative” column, filled for every other module type, is empty on the SIM808 row.
| Type in the notice | Alternative part numbers named |
|---|---|
| SIM800A | 2 (S2-10761, S2-10763) |
| SIM800F | 1 (S2-10768) |
| SIM800L | 2 (S2-10766, S2-107CC) |
| SIM868 | 1 (S2-108J1) |
| SIM868E | 1 (S2-108J8) |
| SIM800C | 5 (S2-1068S, S2-108K7, S2-1068T, S2-108K9, S2-108KG) |
| SIM808 | 0 |
No named successor
The notice lists alternatives for the SIM800A, F, L, 868, 868E and 800C, and none for the SIM808. The fitted module is marked S2-10606-Z1F01, an orderable the notice’s own SIM808 line (S2-1060C) does not name, so whether this board’s exact variant falls inside the phase-out is not established from any SIMCom document.
A rebuild is a radio change
The SIM808 generates the 2.8V rail the RTS pull-up returns against, runs directly from the battery rail, and takes host data through a series diode with no external pull-up. SIMCom’s guide gives that receive pin a pull-down reset state and documents no pull-up on it, so what returns the net high is not established from a published SIMCom document. A replacement is qualified on all three, plus a new AT command set.
This is the failure mode a cross-reference tool cannot see. Parametric search indexes silicon; these three lines carried no lifecycle field at any authorized distributor on the audit date, so they do not appear in a parts-risk report built from those feeds. No public lifecycle record was found for any of the three on the audit date, and none of the three is confirmed discontinued. A rebuild still has to source a part that no lifecycle feed covers.
SIM card socket. Mouser lists a “…512 2A” variant, one character longer, with no lifecycle field anywhere on the page.
Micro USB charging connector. The only public records found were the maker’s drawing and a drawing Adafruit hosts on its own servers.
3.5 mm TRRS headset jack. No authorized distributor listing; maker’s drawing page only.
A BOM line deserves a lifecycle check when one manufacturer stands behind it, whatever the part does. These three passed every check that looks at semiconductors, and would have passed this audit too under its previous scope rule, which exempted connectors as a class.
Its authorized distributor status field reads Not For New Designs, and it sits on a peripheral: its base connects to the module’s PWM1 output, so a board rebuilt around a different radio loses a notification buzzer here. The radio, power and data paths are unaffected.
Forecast & verdict
“SIM808” names more than one physically different module, and the board part number never changed. Adafruit’s own revision history records a move to a version 2 module in December 2015 with newer GPS silicon (MT3337, not MT3336) and a different GPS command set, documented under the same product ID, with no new board part number. Firmware written against a late-2015 board does not necessarily run on the same board bought weeks later.
The vendor’s whole cellular line is unavailable: of fourteen products in Adafruit’s cellular category, thirteen read “No longer stocked” and one “Out of stock.” The FONA 800, the FONA 808, the bare SIM808 module and all four FONA 3G variants are among them, so a reader who migrated 800 → 808 → 3G met the same result three times at the same vendor. Those are one retailer’s availability fields rather than manufacturer lifecycle statuses, and they record what one vendor’s catalogue looks like after the module behind it went end of life.
Component clock, the actual cause
29 Dec 2021
SIMCom’s EOL notice: the PA inside the module reached end of life at its chipset vendor. Purchase window closed 30 Apr 2022.
Network clock, a different schedule
2033 at the latest
The UK 2G/3G sunset joint statement (8 Dec 2021) is spectrum policy, unrelated in cause. An obsolescence process keyed to it would have missed the 2022 window by more than a decade.
The verdict: not buildable as designed. The keystone is end of life, its purchase window has closed, and its own notice names no successor. The five lines that read Active do not change that. Any rebuild is a radio change carrying the 2.8V-rail, battery-rail and series-diode UART qualification, and Adafruit’s own page now steers buyers to the Icarus IoT Board V2, a different board on a different radio, so the vendor’s own suggestion is a redesign.
What this audit does not claim. No part or board named is validated as a form-fit-function replacement for any particular design; each is a candidate to qualify in the reader’s own hardware, firmware and test. Statuses are dated, not permanent. The absence of a distributor listing for the three connectors is a sourcing observation made on the audit date and is not a statement that those parts are discontinued. Parts bought from several manufacturers interchangeably were not individually verified and are not counted. Lifecycle, package and availability data is vendor- and distributor-reported. The net observations are readings of the published schematic. Nothing here was measured on a bench.
Frequently asked
Is the SIM808 obsolete because 2G is being switched off?
No. SIMCom’s notice of 29 December 2021 gives the reason as the power amplifier used in the SIM800 series having already reached end of life at the chipset provider. The 2G and 3G sunsets run on their own schedule and would eventually make the module useless, but they are not the cause stated in the notice.
When was the last chance to buy one?
The notice sets purchase orders accepted until 30 April 2022 and final delivery before 31 May 2022. No last-time-buy remains against it; continuation depends on independent-market stock, whose provenance a buyer qualifies.
Why do the connectors matter more than the resistors?
A standard-value resistor is bought from a dozen makers to the same spec. The SIM socket, micro USB connector and headset jack each resolve to one manufacturer’s part number, and no authorized distributor listing was found for any of the three. Replacing a connector also changes the footprint, so the replacement is a PCB revision.
Are all SIM808 modules the same part?
No. Adafruit’s revision history records a change from a version 1 to a version 2 module with different GPS silicon (MT3337 instead of MT3336) and a different GPS command set. The board part number did not change across that transition, and Adafruit publishes separate v1 and v2 command documents for the same product name.
What did SIMCom offer as a replacement for the SIM808?
Nothing in that notice. The alternative column is filled for the SIM800A, F, L, 868, 868E and 800C, and is empty on the SIM808 row. SIMCom declares in the same document that “this change will not affect the customer application.” The declaration covers the change SIMCom is announcing, and the SIM808 row carries no alternative for it to cover.
Can the board be rebuilt with an LTE module instead?
An LTE module is a redesign. The SIM808 generates the 2.8V rail the RTS pull-up returns against, draws its own supply from the battery rail, and receives host data through a series diode with no external pull-up, and what returns that net high is not established from a published SIMCom document. A replacement is qualified against all three, plus a new AT command set and antenna arrangement.
Why does an obsolete power amplifier take a whole module with it?
A cellular module is a small assembly with its own bill of materials. When a part inside it goes end of life and no pin-compatible equivalent exists at that level, the module maker faces the same requalification burden its customers do, on a part it cannot redesign around cheaply. Retiring the module transfers that decision outward to the boards built on it.
Why does the diode on the receive line matter?
Section 4.6.2 of the SIM808 hardware design guide gives “Isolation circuit by diodes” as a reference circuit for a 3.0V or 3.3V host UART, and attaches a condition: “when a diode used to isolate voltage cross, customer should notice that there’s voltage drop on the diode. And the signal’s voltage level should meet the customer’s electrical character. The recommend diode is Schottky diode e.g. RB551V-30TE-17 and SDM20U40.” The board carries 1N4148 silicon diodes on all four lines. The arithmetic behind that recommendation is in the same guide: it puts the module’s low-level input maximum at 0.7V. In this scheme the module’s receive pin cannot sit lower than the host’s low level plus the diode’s forward drop, so the entire low-level budget is the drop itself, and a silicon junction spends more of it than a Schottky does. The guide leaves the number as the reader’s to check against their own levels, and the same check applies to any replacement radio.
Method & sources
- Scope
- The source test, stated under the ledger in section 02: a line is audited when it resolves to one manufacturer’s orderable part number, whatever the part does.
- BOM source
- Component placement and every net observation parsed directly from Adafruit’s published EagleCAD files, 105 parts across 42 nets. Some part numbers printed above are not the schematic’s own value field. The buffer’s ,118 and the ESD array’s .TCT are packing suffixes on the distributor orderables. The socket’s C707 10M006 512 2 and the micro USB connector’s 20329 are the EAGLE package names C707_10M006_512_2 and 4UCONN_20329, whose library entries link to the makers’ drawings.
- Provenance
- SIM808 status read from SIMCom’s own end-of-life notice. Every other status was read from a DigiKey Part Status field in a browser on the audit date, because DigiKey and the Microchip and ROHM product pages do not serve to an automated fetch. The three connectors returned no authorized listing, reported as an absence and not converted into a status. The module marking S2-10606-Z1F01 was read from the silkscreen of a physical unit on 30 Jul 2026, a first-party observation rather than a published record.
- Re-check
- Parts last verified 2026-07-30; next scheduled re-check 2026-10-28. Every lifecycle status can change after the audit date.
Sources · public, primary
About the author
Related reading
Editorially independent and from public sources only; lifecycle, pin and rating data is vendor-reported, not independently audited. Alternates are candidates to validate in your own design. Confirm every detail with the manufacturer before committing.
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