I assume that you're using a + as the international code (for example 07743 would become +447743 for a UK number) then instead of taking the first 0 from the number and adding a +* (*being the area code such as 44 for the UK) try adding a 00*.
For example, the following are all the same phone number:
07711223344
+447711223344
00447711223344
The last 2 can be used internationally. I hope this helps.
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