Hi Beau,
Well, this is not an easy question to answer in a few lines as it's more a troubleshooting exercise than a general query, but I'll try. For MGCP gateways, there are different places in CUCM where you can configure the manipulation of the incoming calling party ID. Translation patterns are just one of the mechanisms but when using MGCP, you have greater control than using your dialplan for this:
-in the GW device configuration page, you have a section to transform the calling party number based on how the call is labelled: national, international, etc. This label is applied by the carrier when routing the call and so the GW just trusts this info in the Q.931 message and the CUCM applies the transformation based on that.
-in the Device Pool page, you have the same set of settings for incoming calling number transformations. This is the next place where you can configure those and second in priority (GW settings come first)
-in the Service Parameters page (under Advanced-->Device PRI and MGCP gateway) you also can configure this at a system-wide level. The configuration on the specific device pool and then on the gateway itself take priority though.
So, I'd say, check those settings first. Remember that the GW config takes priority over the Device Pool and that the DP takes priority over the Service Parameters.
After you look there, I'd clear completely any translation patterns just to make sure nothing interferes with what you get from the carrier. Do some traces there. What's the number they send to you? Is Europe PRI the best match in protocol for Korea? Check with your PSTN provider how they "label" the calls into national, international, etc..
As I said, it's not easy (as always when troubleshooting dialplan issues) and it requires time to find out where the root cause is. The above should help you making sure your system is not applying any modifications than the ones desired. From then on, it's also a matter of checking with your PSTN provider.
Cheers,
Jose
