The setup is a GSM gateway, where I am trying to bridge all incoming calls to the included sims to an external number.

The logs are: https://pastebin.freeswitch.org/23714

While trying a call to one of the sims, a ring or two can be heard followed by an immediate busy tone, signifying disconnect, which is corroborated by the logs. Why is this sudden disconnect originating? Can someone kindly help?
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Sudhanshu