It's not likely, but there is an error in Mew's original dial plan that might be confusing the SPA.
"00x.S0" is illegal because "S0" tells the SPA to call immediately, but "00x." says that the digit string is of indeterminate length. How is the SPA supposed to know when you are finished dialing, so that it can immediately place the call? S0 only works with fixed length digit strings.
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