I had the same problem and thanks to you guys, it was solved! :) Just in case, I am replying for reference.I was configuring Cisco 2801 router with IOS c2801-adventerprisek9-mz.124-24.T8.bin and connecting to PSTN. Location is also Indonesia.Followin...
Is this is the checkbox you are referring to? (attached image)I had the same problem and it all solved by ticking this particular checkbox. p.s. Sorry for being 4 years late, but I hope this helps others in the future. :)