there is MGW config for each separate 'msc', but the MGW settings are stored only once globally
In osmo-bsc.cfg, the MGW is configured in the 'msc' subsections.
There can be any number of MSCs, each with a different MGW config, but since the MGW config is stored in gsm_network, the last one wins.
What is the intention here, allow a separate MGW for each MSC? In that case we should move the MGW config from gsm_network to bsc_msc_data.
Or should the BSC have a single MGW? In that case we should deprecate the MGW config under 'msc' and move it to 'network'.