Abroad - Can't Call Due to Invalid MMI Code?
 

I have a Verizon Galaxy S3, not rooted, running Jelly Bean 4.1.2. I'm in Israel and have a local SIM in.

Phone works fine to call, text, and for internet. However, I cannot dial *XXX. For example, the phone number for HOT Mobile is *6053, but I can't call. Instead, I see "USSD code running" followed by "Connection problem or invalid MMI code."

The issue is not with the local carrier because these calls go through when the SIM is in another phone. I spoke to Verizon and she said she never heard of MMI code and that it's not their problem - "it's clearly a problem with the 3rd party carrier."

Has anyone encountered this issue before and know how to solve it?

Some people on google forums have said you can add a comma to the end of the code and that may work, it tells them where the mmi code ends and the rest starts.

Others have said to put a plus in front of the first number

So in your case, instead of *6053

try

*6053,

or

*+6053

Of course, for as many people saying it worked there were others saying it didn't, so past results are no guaranty of future whatevers.

The comma didn't work, but the plus did. Thanks so much!! Tried multiple numbers and they all worked. Really appreciate it!
(I tried googling first, but I couldn't figure out the responses)

OK, now I have a different issue. How do I change the voicemail number? Right now, if I hit "Voicemail," it dials *86 which is VZW's voicemail number. I tried changing it to HOT Mobile's voicemail number by going to Phone, Call Settings, Voicemail Settings, and edited the number there. But it said "Voicemail number change unsuccessful."

Any ideas how to change that?

I seem to recall it being a setting in the phone app.

Changing the Voicemail number?