use strict;
my $msg= 
"INVITE sip:paka@36.212.176.92 SIP/2.0
To:samir <sip:paka@36.212.176.92>
Via: SIP/2.0/udp 36.212.176.90:5060;branch=z9hG4bk_Vn
Via: SIP/2.0/udp 36.212.176.66:5060;branch=z9hG4bk_oo
From: sanjay<sip:sanjay@36.212.176.90>
Call-ID: _Vn8TZTk2H@36.212.176.90 
CSeq: 215 INVITE
Max-Forwards: 70
Contact: sanjay<sip:sanjay@36.212.176.90:5060>";

my @fields = split /\n/, $msg;

my %config = (
  URI =>           { regex => qr/^INVITE\ssip:/},
  To =>            { regex => '^To:'},
  From =>          { regex => '^From:'},
  Via =>           { regex => '^Via:'},
  Via1 =>          { regex => '^Via:'},
  Call_ID =>       { regex => '^Call-ID:'},
  CSeq =>          { regex => '^CSeq:'},
  MaxForwards =>   { regex => '^Max-Forwards:'},
  Contact =>       { regex => '^Contact:'},
 );
my %cnf;
 foreach (@fields) {
  chomp;
  foreach my $c (keys %config) {
    if (/$config{$c}{regex}/) {
      $cnf{$c} = $_;
      last;
    }
  }
}