I've attached patch used in this PPA. This patch wasn't submitted upstream. It simply forces Modem Manager 1.2.0 to use unencoded USSD request string first (like in earlier Modem Manager versions <= 0.6.2). It works at least for ZTE 180 modem and there is no side effects for modems that work fine without this patch (e.g. Huawei E1550, E173u1).
I've attached patch used in this PPA. This patch wasn't submitted upstream. It simply forces Modem Manager 1.2.0 to use unencoded USSD request string first (like in earlier Modem Manager versions <= 0.6.2). It works at least for ZTE 180 modem and there is no side effects for modems that work fine without this patch (e.g. Huawei E1550, E173u1).