Moving a Nokia site from the Flexi Multiradio 10 System Module (FSMF) to AirScale means replacing the FSMF and its FBBA/FBBC extension sub-modules with an AirScale system module: a subrack (AMIA indoor or AMOB outdoor), one common plug-in unit (ASIA or ASIB) and one or more capacity plug-in units (ABIA for 2G/3G/4G, ABIO for LTE and 5G NR). Because ABIA and ABIO both support the OBSAI fronthaul used by Flexi radios, the radios on the mast can often stay in place during the first phase. This guide explains the path step by step and what to check when sourcing used units.
Why operators move from FSMF to AirScale
The Nokia FSMF (472181A) is a weatherproof 3U system module that runs GSM, WCDMA and LTE in single-RAN mode. Its capacity is extended by adding FBBA or FBBC baseband sub-modules. It remains a reliable unit and is still widely deployed, but it is a fixed-architecture box: once the sub-module positions are used, the only way to grow is to add another system module.
AirScale uses a modular subrack instead. Capacity is added by inserting plug-in cards, and newer capacity cards add LTE and 5G NR processing that the Flexi Multiradio 10 platform was not designed for. In practice the move is usually driven by one of three needs:
- More LTE capacity or more cells than an FSMF with extension sub-modules can carry.
- Preparing the site for 5G NR on the same baseband.
- Standardising spares on one baseband platform across the network.
Flexi Multiradio 10 vs AirScale: the building blocks
The table below maps the main Flexi Multiradio 10 components to their AirScale counterparts. Product codes are the ones normally printed on the unit label.
| Function | Flexi Multiradio 10 | AirScale |
|---|---|---|
| Housing | FSMF core module in 3U weatherproof casing | AMIA indoor subrack (473098A), 19-inch, 128 x 447 x 400 mm; AMOB for outdoor sites |
| Control and transport | Integrated in FSMF (EIF1 electrical GE, EIF2 optical) | Common plug-in unit: ASIA (473095A) or ASIB (473764A) |
| Baseband capacity | FSMF plus FBBA / FBBC sub-modules | Capacity plug-in units: ABIA (473096A), ABIO (475266A) |
| Radio technologies | GSM, WCDMA, LTE | ABIA: GSM, WCDMA, FDD-LTE, TD-LTE; ABIO: LTE and 5G NR |
| Maximum configuration | One module with extension sub-modules | AMIA: up to 2 common and 6 capacity plug-in units |
| Ingress protection | Weatherproof, outdoor without cabinet | AMIA: IP20 (indoor or inside a cabinet) |
One practical point is visible straight away: the FSMF can be mounted outdoors on its own, while the AMIA is an IP20 indoor subrack. If the existing FSMF sits on a pole or wall without a cabinet, you need either a cabinet for the AMIA or the outdoor AMOB subrack. In Nokia swap projects the AMOB has been installed on top of an existing Flexi stack.
Step-by-step upgrade path
Step 1: Survey the existing Flexi site
Record the FSMF product code, any FBBA/FBBC sub-modules, the transport connection (electrical or optical on EIF1/EIF2), the DC power arrangement and every radio module on site with its band and product code. Typical Flexi radios include the FRGU (2100 MHz), FXED (1800 MHz) and FRHF (2600 MHz). This list decides which AirScale cards you need.
Step 2: Choose the subrack
For indoor rooms and cabinets, the Nokia AMIA subrack is the standard choice. It takes a minimum of one common and one capacity unit and runs from -48 V DC nominal (-40.5 V to -57 V), so it fits the DC plant most Flexi sites already have. Check rack depth (400 mm) and front-to-back airflow before ordering.
Step 3: Choose the common plug-in unit
The common unit handles control, transport and synchronisation. ASIA is the first-generation card; ASIB is the later card with 7.5 Gbps IPsec throughput. The choice matters for the next step: the ABIO datasheet lists ASIB and ASIL as its common units, not ASIA. If 5G NR on ABIO is part of the plan, start with ASIB. We cover the differences in detail in Nokia AirScale ASIA vs ASIB: What Are the Differences?
Step 4: Choose the capacity plug-in units
Capacity cards replace the processing that the FSMF and its FBBA/FBBC sub-modules did:
- Nokia ABIA is the multi-RAT card for GSM, WCDMA, FDD-LTE and TD-LTE, with 6 x SFP+ ports, CPRI up to 9.8 Gbps and OBSAI 3/6 Gbps. Per card it handles 36 GSM TRX, 12 WCDMA cells, or 12 LTE cells 2T2R at 20 MHz (6 cells 4T4R).
- Nokia ABIO is the LTE and 5G NR card, with 9 x SFP28 ports, eCPRI 10/25 Gbps, CPRI up to 9.8 Gbps and OBSAI 3/6 Gbps, and 14 Gbps downlink / 7 Gbps uplink L1 throughput. It does not cover GSM or WCDMA.
A site that still carries 2G or 3G traffic therefore needs at least one ABIA, even when ABIO is added for LTE and NR capacity.
Step 5: Decide what happens to the radios
Flexi RF modules connect to the system module over OBSAI. Since both ABIA and ABIO support OBSAI 3/6 Gbps, a phased migration is possible: swap the baseband first and keep the existing Flexi radios, then replace radios band by band later. Operators have done exactly this, keeping Flexi RF modules on certain bands for several software releases after the AirScale swap. Note that 4T4R or 5G NR on a band normally requires a newer radio, so plan radio replacement where new features depend on it.
The reverse is also useful. Several AirScale radio modules, such as the AirScale ARDA (900 MHz, 6T6R), list both FSMF and AirScale as supported system modules. If a Flexi radio fails before the baseband swap, an AirScale radio can be installed on the FSMF now and moved to the AirScale system module later.
Step 6: Software and commissioning
Supported card and radio combinations depend on the software release running on the site. Before the swap, confirm that the target release supports the exact hardware mix (common unit, capacity cards and every radio on site), and plan the new site configuration file and transport parameters. Keep the FSMF as a fallback until the AirScale site is stable.
What to check when buying used AirScale parts for a swap
- Product codes: confirm 473098A (AMIA), 473095A (ASIA), 473764A (ASIB), 473096A (ABIA) and 475266A (ABIO) on the label, not just the card name.
- Common/capacity pairing: do not pair ABIO with ASIA.
- SFP modules: ABIA uses SFP+ and ABIO uses SFP28; the optics on the radio side must match the link rate and fibre type.
- Physical condition: check backplane connectors, card guides and fan modules in the subrack, and the SFP cages on each card.
- Power-on test: ask for a test record showing each card boots and is recognised in the subrack.
FAQ
Can I install ABIA or ABIO directly into an FSMF?
No. ABIA and ABIO are AirScale plug-in units and need an AirScale subrack (AMIA, AMOB or AMOD) with a common unit. The FSMF uses FBBA/FBBC sub-modules for extra capacity.
Can I keep my Flexi radios after moving to AirScale?
Often yes, because ABIA and ABIO support OBSAI 3/6 Gbps fronthaul. Confirm that your target software release supports each radio model before relying on this.
Is ASIA enough for an upgrade?
For a 2G/3G/4G site using ABIA, ASIA can work. If you plan to add ABIO for LTE or 5G NR capacity, choose ASIB, since the ABIO datasheet lists ASIB and ASIL as its common units.
Does the AMIA work outdoors?
The AMIA is IP20 and is meant for indoor rooms or cabinets. For outdoor sites without a cabinet, use the AMOB outdoor subrack or install the AMIA inside an outdoor cabinet.
Source tested Nokia Flexi and AirScale units
We supply used and refurbished Nokia baseband and radio units for both phases of a swap, from FSMF spares for sites that stay on Flexi to AMIA, ASIB, ABIA and ABIO for AirScale upgrades. Browse the full Nokia range. All units are tested before shipment and come with a 90-day warranty, and we ship worldwide in secure packaging. Contact us on WhatsApp at +86 187 3329 4669 or +86 139 3088 8705, email jack@telecombts.com, or use the form at https://telecombts.com/contact-us/ with the product codes and quantities you need.