Traditionally, OEMs have not permitted VoLTE on networks where 1:1 testing has not been performed. This approach tends to impact the smaller MNOs and MVNOs which can’t present a compelling business case for OEMs to justify dedicated rollout support, unlike their larger counterparts.
In addition, it is impractical for all devices to be tested in all networks given the numbers of devices and networks facing challenges or yet to launch VoLTE. Around 47% of LTE networks are yet to launch VoLTE – with many hundreds of MVNO networks wishing to as well.
Source: GSMA Network Closures Report, March 2025
Samsung’s IR.25 Binary
Samsung has addressed this issue via the launch of its “IR.25 Binary” build which permits VoLTE on non-partner operator networks. Currently on the Samsung S.25 device, it will also be applied to older, already-launched models which are using Android OS v15.
In terms of IMS configuration settings, Samsung devices will apply the network preferred settings if they are present in the GSMA Network Settings Exchange database – the device configuration periodically syncs with the database to ensure it remains up to date.
For network operators, this is a streamlined process. They simply need to ensure their standardised configuration values are updated within the Network Settings Exchange.
If the given network settings are not in the Network Settings Exchange, then Samsung will apply default IMS settings in line with GSMA Profile #4 (P#4).
The two recommended IMS profiles
The GSMA, via its NRG WG, previously defined six IMS profiles which were documented in GSMA PRD IR.25 and were as follows:
- Profile#1 and #2 (P#1 and P#2) – VoLTE and legacy SMS
- Profile#3 and #4 (P#3 and P#4) – VoLTE and SMSoIP
- Profile#5 and #6 (P#5 and P#6) – VoLTE, VoWiFi and SMSoIP
Based on industry feedback, it was proposed to narrow the six down to just two, promoting commonality, facilitating interoperability and reducing the overall testing burden in the industry:
- Profile#4 (P#4)
- Profile#6 (P#6)
Note that P#6 is a superset of P#4 and adds VoWiFi on top of P#4.
Futureproofing with P#6 & VoWiFi
Samsung isn’t stopping here. An internal process is underway to support GSMA Profile #6 (P#6). P#6 is a superset of P#4, adding Voice over Wi-Fi (VoWiFi) capabilities. This will be the default settings for non-partner operator networks that have not uploaded settings to GSMA Network Settings Exchange.
GSMA and Samsung are also working towards rolling out these features on devices running on older Android versions.
Impact on the industry
The Samsung initiative offers a major step forward. It enables all M(V)NOs to acquire a Samsung device and test for interoperability on their network. M(V)NOs that have yet to launch VoLTE are strongly encouraged to adopt either P#4 or P#6 as their preferred IMS settings and/or upload their settings to the Network Settings Exchange database.
In addition, other OEMs that still do not allow VoLTE on unknown networks are strongly encouraged to copy the Samsung example and permit VoLTE on such networks – applying either the correct network settings through GSMA Network Settings Exchange or the P#4/P#6 as default settings.
Testing recommendations
After adopting either the P#4 or P#6 settings, M(V)NOs are encouraged to have their network accredited via GSMA Interoperability Testing to prove compliance with GSMA PRD IR.25. While it is possible in theory for Samsung devices to work on an unaccredited network, any issues encountered will be difficult to resolve. On the other hand, the GSMA can facilitate a dialog between an M(V)NO and Samsung in the event of the network previously having been accredited.
The GSMA records all network accreditations on its Interoperability Testing results page and informs all OEMs currently accessing the GSMA Network Settings Exchange platform.
It is recommended that OEMs, particularly smaller companies, have their devices accredited against P#4 or P#6. This can be done either by the GSMA via its Interoperability Testing service or through an in-house (“self-accreditation”). In the case of self-accreditation, traces must be provided to the GSMA as evidence of compliance to IR.25. Again, the GSMA publishes all such accredited devices on its results page and informs the M(V)NOs currently accessing the Network Settings Exchange platform.
Summary
There are many ways the mutual adoption and support of P#4/P#6 by M(V)NO networks and devices in conjunction with devices following the Samsung initiative helps businesses and the industry:
- Reduces the testing burden by promoting commonality, decreasing the need for exhaustive 1:1 testing.
- Empowers smaller operators by making advanced features accessible, even without direct OEM partnerships.
- Builds trust byenabling reliable interoperability based on adherence to common standards.
- Accelerates rollouts, speeding up VoLTE deployment and facilitating the crucial shutdown of legacy 2G/3G networks.
If you’d like to find out more about GSMA Interoperability Testing, please visit our website here. For more information about GSMA Network Settings Exchange, visit our website here.
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