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In the days before Android, buried deep in the network settings of my old phone were two options called Preferred Networks and Forbidden Networks was an option called Preferred Networks, and I have also heard of Forbidden Networks. These were used for roaming: when the home network was not available, the phone would not simply grab the first available network but compare the list of currently available networks to the Preferred & Forbidden Networks: it would never try to roam into a forbidden network, and if one of the visible networks was on the Preferred Networks list, it would try that network first. The lists were stored on the SIM.

Note that this has nothing to do with APNs or network types – this setting is entirely about network operators.

Does Android still use these lists? If so, is there a way to view/edit these lists on Android?

  • I don't think Android deals with this natively (at least I've never seen/found/heard-of such an option). Which does not mean there's no solution: see my answer here. – Izzy Jul 12 '15 at 20:50
  • Actually, reconsidering it – I use three different SIM cards from different countries in my phone, all of them either Vodafone or Vodafone partner networks. When roaming with any of these cards, the phone will almost invariably pick the local Vodafone network or the partner network, falling back to other networks only when the former is not available. As far as I remember, the cards have those networks in their Preferred Network list – thus apparently Android still honors that. Which leaves us with the questions: is that the same for Forbidden Networks? And how can I edit the lists? – user149408 Aug 1 '15 at 20:31
  • I don't think so. What I rather suppose is happening here is some provider flags making Android prefer those networks. But I've got no knowledge on that level. – Izzy Aug 4 '15 at 9:07
  • Through research I found out that Preferred and Forbidden Networks are part of the SIM card spec. While Preferred Networks are a user-editable preference, Forbidden Networks are not. They are a list of four entries handled by the phone: whenever a network rejects a registration request, its MCC/MNC is stored (dropping the oldest entry if the list is full) so the phone will skip these in the future. Most likely it's up to the modem if and how it handles both – maybe modems nowadays handle everything internally without relying on the SIM. – user149408 Jan 25 '16 at 13:51
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Deselect international OR select the service provider's roaming options under SIM tools, this may may help to avoid any forbidden network scenario.

  • In a limited number of scenarios this might work. If you run a custom ROM, you can also edit the lists of networks considered not roaming (which are per MCC/MNC of the SIM issuer) and then disable roaming—this will effectively whitelist the networks considered not roaming, and prevent use of all others. – user149408 Mar 12 '17 at 17:00

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