Hi Thyda
When you set "exten => _.,1,Dial(SIP/${EXTEN})" Asterisk assume
"_.", an match everything on your dialplan including special
extensions as "i", "h", etc., these will cause problems
onto your system.
If you need to match one or more digits you can use _x and _x.
_x it mean only one pattern digit form 0 to 9
_x. any pattern digit from 0 to 9 and dot it mean remnant digits could be 2 or
3, 4 ... etc., so what ever you dial on sip it will be valid.
Mc GRATH Ricardo