The document provides best practices for mobile VoIP, emphasizing the importance of managing latency, reliability, and battery life when using various codecs and network settings. It discusses configurations for different devices, challenges with NAT timeouts, and how to effectively use TCP and TLS for connections. Additionally, it highlights the need for optimization based on network type and device capabilities to improve overall VoIP performance.

1. MobileVoIP
Best
Practices
Joachim Vanheuverzwijn aka Zoa
Joachim@zoiper.com

2. 1
Latency
Quality
Reliability
Battery Life

3. 2
o End to end latency - max 500ms!

4. 3
o Network Latency
o Audio Latency
o Algorithmic Delay

5. 4
o Network (best case)
2G: 400ms
3G: 80ms
LTE: 20ms
WiFi: 10ms
+ transit!

6. 5
o Network Latency
o Audio Latency
o Algorithmic Delay

7. 6
Available for android, (ios, wp8)
https://play.google.com/store/apps/details?id=com.zoiper.audiolatency.app&hl=en

8. 6

9. 8
Phone Latency @ 8kHz (ms) Latency @ 44.1kHz (ms) Latency @ 48kHz(ms) Android version
Nexus 5 170 155 108L
Nexus 5 170 156 1104.4.4
Samsung Galaxy S4 (i9505) 143 121 1684.4.2
Motorola RAZR i(XT890) 176 249 1234.0.4
Nexus S 235 164Not supported 4.1.2
Sony Xperia U 167 173 1672.3.7
HTC Incredible S 333 173 1764.0.4
Motorola Droid RAZR(XT912) 250 190 2584.1.2
Motorola RAZR D1(XT914) 319 217 2074.1.2
Alcatel OT Idol Ultra 6033X 303 217 2114.1.1
Asus FonePad7 257 212 2124.4.2
Vodafone Smart Mini/TCT 875 304 227 2334.1.1
Oppo R819 244 274 2364.2.1
Samsung GT-S5300 814 389 3162.3.6
Samsung Galaxy S3 822 328 3764.0.4
Asus Memo Pad HD7 313 202 2214.2.1

10. 9
o iOS superior
o Android 5 > 4.4 > 4.2 > …
o Nexus 4, 5, Galaxy Nexus
o Speakerphone adds 20ms

11. 10
o iOS 20ms
o Android 100 – 800
o WP8 200ms
o 3g: 80ms
o LTE: 20ms
o WiFi: 10ms
o All to or from PSTN - OK
o All to or from iOS - OK
o Android / wp8 to android / wp8 - ?

12. 11
Latency
Quality
Reliability
Battery Life

13. 12
 No SPEEX!
 Use OPUS with FEC
 8 or 16kHz
 Pick a phone with native
sample rate != 44.1kHz

14. 13
 Native: 44.1kHz
 Open: 48kHz
 Codec: 8kHz
 Open at native sample rate or
codec sample rate!

15. 14
Latency
Quality
Reliability
Battery Life

16. 15
Signaling:
Outgoing Calls
Incoming calls

17. 16
Common configuration:
UDP:5060

18. 17
SIP INVITE too big for the network ?

19. 18
UDP fragmentation issue
Last part of the SDP never arrives
Unexpected media negotiation
It’s EASY… Use TCP

20. 19
Oops!
Android drops SIP traffic on TCP
ALG firewalls often break TCP SIP

21. Meet Olle
Today, 4PM
The open Communication
Revolution Agenda

22. 16
Oops!
Android ships with broken
certificate store*!
(and windows phone 8.0 does
not have an accessible one)
*”slightly” dramatized to annoy Olle!

23. 21
Use:
TCP != 5060
TLS (443)
IAX2

24. 22
Incoming Calls

25. 19
SIP Registrations
This is my IP and PORT

26. 19
Registrations & Server load
Server Registration rate limiting

27. 20
Registrations & High server load?
• Put reasonable limit / 24h

28. 23
Registrations & NAT

29. 24
NAT Time-Outs:
UDP = 30s ~ 2.5m
TCP = 2 hr minimum
(RFC5382)

30. 25
if
NAT Time-Out
<
registration expiry time
=
No incoming calls!

31. 26
NAT Time-Outs:
UDP = 30s ~ 2.5m
Too high server load!
Use TCP
TCP timeout = 2h (RFC5382)

32. 27
Ooops!
• 3G/4G will reset idle TCP connections after 10 to 120m
• Many NAT’s do not follow the RFC for TCP
• Cheap NAT’s have limited memory for mapping db

33. 28
Ooops!
• 3G/4G will reset idle TCP connections after 10 to 120m
• Many NAT’s do not follow the RFC
• Cheap NAT’s have limited memory for mapping db
re-register = 30s?

34. 29
iOS only allows wakeup after 10min

35. 30
iOS only allows wakeup after 10min
Server OPTIONS every 30s ?

36. 31
iOS will kill the app.
Limit
OPTIONS
PUBLISH
NOTIFY

37. 32
iOS kills the app?
30s TCP Keep Alive?

38. 33
Many keep alive packets
decrease battery
(and increase bandwidth)

39. 34
Test Setup:
RangeNetworks Dev Kit (OpenBTS)
Couple of phones
4 simcards
2 WiFi AP

40. 35
Test Setup:
Inconclusive
Data & graphs
from Michigan University, AT&T,
Nokia whitepapers.

41. 36
DCH
PCH
FACH

42. 37

43. 38
*#*#0011#*#*
*#*#197328640#*#*
*#*#7378423#*#*
*#*#4636#*#*
*3001#12345#*

44. 37
*#*#0011#*#*
*#*#197328640#*#*
*#*#7378423#*#*
*#*#4636#*#*
*3001#12345#*

45. 40
* Something is wrong with the scale here

46. 41
* Something is wrong with the scale here

47. 42
* Something is wrong with the scale here

48. 43
30s 60s 600s 3600s
Wifi* +2% +1.3%
3G x12 x6 x2 x1.1
LTE x20 x10 x2.5 x1.2
Radio Energy Usage
*WiFi is rarely the only active radio
Radio is not the only battery eater
Other processes are using the radio too

49. 44
What is the optimal setting for the
Keep-alive ?

50. 45
What does google use ?
( Dial *#*#8255#*#* or *#*#426#*#* )
• every 28 minutes on cellular
• every 15 minutes on WiFi
Joachim@zoiper.com

51. 45
What does google use ?
( Dial *#*#8255#*#* or *#*#426#*#* )
• every 28 minutes on cellular
• every 15 minutes on WiFi

52. 46
o Mobile app for timeout detection.
o Check and adjust values for every network.

53. 47
WiFi (Pfsense)
TCP: more than 15h
UDP: 30s
Globul 3G
TCP: 1800s or 3600s
UDP: 120s
Mtel 3G
TCP: 600s
UDP: 120s
Max Telecom LTE
TCP: 3600s
UDP: 180s

54. 481
Use TCP !=5060
TLS 443
TCP timeout as needed
Register >360s

55. 491
Oops
No Background on WP 8 

56. 491
Oops
No Background on WP 8 
It’s EASY…PUSH!

57. 52
PUSH Limitations:
- It is relatively slow
- Requires server changes
Invite queue, registration time

58. 53
PUSH Limitations:
iOS + Android push is per app!

59. 54
PUSH Advantage:
Works with APP stopped

60. 55
So what is the (best) solution ?

61. 56
So what is the (best) solution ?
Use TCP/TLS + Push!

62. MobileVoIP
Questions ?
Joachim Vanheuverzwijn aka Zoa
Joachim@zoiper.com