The history of calls and messages are stored in a MySQL database. For safety reasons (i.e. to not modify the database itself), we make a copy of it and look into it:
Another easy way to look for something particular is just grep from a .dump output:
$ sqlite3 history.sqlite .dump | fgrep 'Willkommen in '
INSERT INTO "text_events" VALUES('ofono/ofono/account0','FONIC','2015-08-31T10:04:20+0200-1','FONIC','2015-08-31T08:04:24.000',0,'Willkommen in Italien! In Ihrem Tarif zahlen Sie für Gespräche in der EU 0,22 €/min.; eingehende Anrufe 0,05 €/min., SMS 0,07 €. Notruf 112 kostenlos, Info +4917688864243',0,0,'2015-08-31T10:06:25.017','');
INSERT INTO "text_events" VALUES('ofono/ofono/account0','FONIC','2015-09-12T13:14:14+0200-1','FONIC','2015-09-12T11:15:26.000',1,'Willkommen in Österreich! In Ihrem Tarif zahlen Sie für Gespräche in der EU 0,22 €/min.; eingehende Anrufe 0,05 €/min., SMS 0,07€. Jetzt EU-Paket 100 Minuten (ein- und ausgehend/4,95€/7 Tage) buchen: Start FonicEU100Min per SMS an 36642.. Notruf 112 kostenlos, Info +4917688864243',0,0,NULL,NULL);
Note: The column accountId (here: "ofono/ofono/account0") is the reference to the used SIM1 or SIM2 during the call. It can be probed which SIM is which account with: