By the way, I had a look online if I can find any info about this. It's hard finding any info on telcel tariffs at all, let alone this condition. Their own website is terribly slow at the moment, but I have been reading a few blogs and forums in Spanish. Nobody seems to mention anything about your particular issue.
However, they seem to have had a tariff change recently. The best summary of all rates is:
Nuevas tarifas telcel
No mention on there about incoming charges for international though.