Delay for up to four (4) seconds when using STUN on certain iPhone systems (thanks Guy Zelkha for the report)

[bennylp]

Delays for up to four (4) seconds are observed with STUN on certain iPhone systems.

Sample: iPhone OS-3.2/arm/iOS-SDK-4.1

18:04:53.291    stunresolve  RX 88 bytes STUN message from 212.64.151.160:4478:
--- begin STUN message ---
STUN Binding success response
 Hdr: length=68, magic=2112a442, tsx_id=fbf145dab360c9f000017327
 Attributes:
  MAPPED-ADDRESS: length=8, IPv4 addr=109.186.67.85:61160
  SOURCE-ADDRESS: length=8, IPv4 addr=212.64.151.160:4478
  CHANGED-ADDRESS: length=8, IPv4 addr=46.38.162.185:4479
  Attr 0x8020: length=8
  SOFTWARE: length=16, value="Vovida.org 0.96"
--- end of STUN message ---

18:04:53.291    stunresolve  STUN mapped address found/changed: 109.186.67.85:61160
18:04:53.299   pjsua_core.c  STUN resolution success, using 212.64.151.160:4478, address is 212.64.151.160:4478
18:04:53.299 stuntsx0x87655  STUN client transaction destroyed
18:04:54.826  stun_simple.c  Warning: unknown attr type 8020 in attr 3. Attribute was ignored.
18:04:54.826  stun_simple.c  Warning: unknown attr type 8022 in attr 4. Attribute was ignored.
18:04:54.828  stun_simple.c  Warning: unknown attr type 8020 in attr 3. Attribute was ignored.
18:04:54.829  stun_simple.c  Warning: unknown attr type 8022 in attr 4. Attribute was ignored.
18:04:57.303   pjsua_core.c  SIP UDP socket reachable at 109.186.67.85:1024
18:04:57.305    udp0x869000  SIP UDP transport started, published address is 109.186.67.85:1024