# Roaming and permanent roaming https://www.datasim.com/technical/roaming/ Quick answer. A device is roaming when it uses a network other than its SIM's home network, under a roaming agreement between the operators. The home network authenticates the device and its data is usually routed back home. Permanent roaming is when a device stays on a visited network indefinitely, which some operators and countries restrict. ## Simple A SIM belongs to one operator, its home network. When the device uses another operator's network, that network is the visited network and the device is roaming. This happens abroad, and it can also happen at home when a SIM from a foreign operator is used. ### How roaming works Operators sign roaming agreements with each other. An agreement lets one operator's customers use the other's network and sets what each pays. Some agreements are made directly between two operators. Others go through a roaming hub, which connects one operator to many partners at once. When a roaming device connects, the visited network asks the home network to check the SIM. The home network confirms who the device is and whether it may use the network. Its data is usually carried back to the home network before it reaches the internet, so the home operator stays in control of the service. ### Why IoT devices often roam Most IoT products are built once and sold in many countries. Fitting a different local SIM for each country is costly to manage. So many IoT SIMs roam wherever they are used, including in the country where the device spends its whole life. A device that lives on a visited network like this is in permanent roaming. ### Where permanent roaming is restricted Roaming agreements were written for travellers who come and go. Some operators do not want devices that never leave, and some countries limit or ban permanent roaming by law or licence rules. In the EU, the roaming rules cover machine-to-machine devices, and operators may limit permanent roaming. The details differ by country, so check them before you deploy. [Permanent roaming rules by country](/technical/permanent-roaming-rules/) sets out the current position. Ways around a restriction include a local SIM profile, a [multi-network SIM](/technical/multi-imsi/) that can switch to a local identity, or an [eUICC](/technical/esim-euicc-mff2/) that can take a local operator's profile. ### What it means for your devices Roaming decides which networks a device can use in each country, and whether it can stay there long term. The table below shows how each DataSIM SIM profile handles it. ## Advanced ### Home and visited networks A SIM's home PLMN (HPLMN) is identified by the MCC and MNC at the start of its IMSI. Any other PLMN the device registers on is a visited PLMN (VPLMN), and the device is roaming. Roaming is defined by the network the device uses, not by where it is. A device with a foreign IMSI is roaming in your own country, and a device can stay on its home network across a border where the home operator's cells reach. ### Roaming agreements A visited operator serves another operator's subscribers only under a roaming agreement. The agreement covers which radio technologies are open to the partner's SIMs, the wholesale charges, testing, billing data exchange and fraud handling. Each technology is opened separately. A partner can have 4G roaming in place and no LTE-M or NB-IoT roaming. Agreements are made in two ways. - **Bilateral**, directly between two operators. - **Through a roaming hub**, where an operator connects once and reaches many partners through the hub's agreements and signalling connections. Signalling and roaming data travel between operators over the IPX or GRX, the private inter-operator IP networks, not the public internet. ### What happens when a device registers In LTE (TS 23.401 ยง4.2, GSMA IR.88), the device attaches to the visited network's MME. The MME contacts the home HSS over the S6a Diameter interface. The HSS sends authentication vectors, so the device is authenticated with keys only the home network holds, and then sends the subscription data that says what the device may use. The home network can refuse the registration at this point, which is also how network-based [steering](/technical/steering/) works. For 5G the equivalent is the visited AMF and the home AUSF and UDM, with the same split: the home network authenticates and authorises, the visited network provides radio and local core functions. ### Home routing and local breakout Once attached, the device opens a data session. The gateway that gives it an IP address and connects it to the internet or a private network can sit in either network. | | Home routed | Local breakout | |---|---|---| | Gateway (PGW in LTE) | Home network | Visited network | | Path | Visited SGW to home PGW over S8, across the IPX | Visited SGW to visited PGW | | IP address and APN | Home network's | Visited network's | | Private APN, static IP, VPN | Work as at home | Need the visited operator's support | | Latency | Adds the trip to the home gateway | Lower | Home routing is the usual arrangement for roaming data. It keeps the device's IP addressing, APN and policy the same in every country, which matters for IoT fleets that connect to a private network or VPN. The cost is the extra path to the home gateway, which adds latency when that gateway is far away. Local breakout gives a shorter path but hands the IP session to the visited operator. IR.88 describes both, along with a variant where traffic breaks out in the visited network under the home operator's control. ### Why most cross-border IoT SIMs roam A product shipped to many countries usually carries one SIM type. Unless that SIM changes identity, the device is roaming everywhere outside the SIM operator's own country. This gives one contract, one APN and one IP plan worldwide, at the price of depending on roaming agreements in every country. Ways to reduce that dependence include [multi-IMSI SIMs](/technical/multi-imsi/), which can switch to an identity from a partner operator, and [eUICCs](/technical/esim-euicc-mff2/), which can download a local operator's profile under the [eSIM standards](/technical/esim-standards/). ### Permanent roaming Permanent roaming means a device stays on a visited network indefinitely, instead of visiting for a while and returning home. For IoT it is the normal case for a roaming SIM. Roaming agreements were designed around travellers, and some operators and countries restrict permanent use. Reasons given include protecting local operators and investment, applying national numbering and registration rules, and keeping service under the local regulator's control. Some countries restrict it by law. Saudi Arabia, for example, allows a foreign SIM in an IoT device for no more than 120 days. [Permanent roaming rules by country](/technical/permanent-roaming-rules/) has the details. ### The EU position Regulation (EU) 2022/612 of 6 April 2022 is the current EU Roaming Regulation. BEREC's Wholesale Roaming Guidelines on its Article 3, which covers wholesale roaming access (BoR (26) 70, 2 June 2026, replacing BoR (22) 147), set out how it applies to machine-to-machine communications, and now also cover requests for LTE-M, NB-IoT and 5G IoT roaming. - M2M services are within the scope of the Regulation (Recital 21). The Regulation's limits on permanent roaming apply to them as they do to other services. - Reasonable requests for regulated wholesale roaming access to offer M2M services should be met where devices roam periodically. - Where M2M devices are used on a permanent basis in a visited network, wholesale access should be subject to commercial negotiation. - Operators are expected to increasingly accept reasonable requests for agreements that explicitly allow permanent roaming for M2M. BEREC suggests charging models suited to low-data devices, such as a price per connected device. - A visited operator may take measures against permanent roaming by a significant share of a partner's customers. Terminating a wholesale agreement on those grounds needs prior authorisation from its national regulator. In practice, permanent roaming for M2M in the EU depends on the commercial agreement between the operators. It is neither guaranteed nor banned by the Regulation. ### Practical points for IoT - Check roaming per technology. 4G roaming with a partner does not mean LTE-M or NB-IoT roaming. - Allow for the home-routing path in latency budgets, especially when the home gateway is on another continent. - Check the permanent roaming position in every country of deployment before you ship. - Understand how the SIM [selects a network](/technical/network-selection/) in each country, since roaming agreements decide which networks it may use. ## Myths - **Myth.** Roaming means a device can use several networks at once. **Fact.** Roaming means using a network other than the SIM's home network. A device is registered on one network at a time, and it can use a visited network only where its home operator has a roaming agreement for that technology. - **Myth.** Permanent roaming is illegal everywhere. **Fact.** A few countries restrict or ban it. Elsewhere it depends on the agreements between operators. In the EU, the Roaming Regulation covers M2M devices, and permanent use is left to commercial negotiation between operators. - **Myth.** A SIM that roams in a country can use every network there. **Fact.** It can use only the networks its home operator has agreements with, and only for the technologies those agreements cover. LTE-M and NB-IoT roaming are agreed separately from 4G. - **Myth.** Roaming data always goes straight to the internet from the local network. **Fact.** Most roaming data is home routed. It travels from the visited network to the home operator's gateway before it reaches the internet or a private network. Local breakout, where the visited network provides the gateway, is the exception. ## Sources 1. [BEREC Wholesale Roaming Guidelines (application of Article 3 of Regulation (EU) 2022/612: wholesale roaming access, M2M, permanent roaming)](https://www.berec.europa.eu/system/files/2026-06/BoR%20%2826%29%2070_Wholesale%20Roaming%20Guidelines.pdf), BEREC, BoR (26) 70, 2 June 2026 2. [Introduction to roaming (Regulation (EU) 2022/612)](https://www.berec.europa.eu/en/all-topics/introduction-to-roaming), BEREC 3. [EPS Roaming Guidelines (home routed and local breakout architectures)](https://www.gsma.com/newsroom/?p=20172), GSMA, IR.88 v29.0 4. [General Packet Radio Service (GPRS) enhancements for E-UTRAN access (roaming architecture)](https://www.3gpp.org/DynaReport/23401.htm), 3GPP, TS 23.401 Checked 30 October 2026.