The settings to setup your SIP device for SIP2SIP are the following:

SIP Account Credentials

Account credentials are used for authentication and authorization of SIP requests performed by the SIP device. Your sip address is:, where XXX should be replaces with the username chosen in the sign up.

Username Username chosen during sign up
Password Password chosen during sign up

username chosen during the account Register must be turned On in order to receive incoming calls. If your SIP devices is smart enough, there is no need to set manually anything else than the above settings. If you need to manually fine tune the configuration see below.

Advanced settings

Server Location

There are multiple SIP servers distributed in multiple geographic locations. To locate them, the SIP device must always perform DNS lookups as defined in SIP standard RFC3263 (NAPTR + SRV + A DNS lookups).

You must never set manually a host address or transport belonging to SIP2SIP server infrastructure into your SIP device as it may and will change over time. Your device must use DNS lookups instead of hardwiring any such settings into your SIP device. For informational purposes, the servers are reachable at the following addresses, but again you must query the DNS to discover them as they may and will change in the future:

Host Port Protocol 5060 UDP 5060 TCP 443 TLS

To use TLS you have to append the port to the outbound proxy setting:


XCAP Root:

Required functionality

To use SIMPLE presence the SIP client must support the following standards related to SIP and XCAP protocols:

  • SIP Presence Agent mode (PUBLISH method) (RFC3903)
  • Event packages: presence and presence.winfo
  • XCAP rls-services and resource-lists for contacts storage (RFC4826)
  • XCAP org.openmobilealliance.pres-rules for authorization rules (OMA XML 1.1)


Additional the SIP end-point may support the following extensions:

  • Event packages: xcap-diff for synchronizing XCAP documents between clients
  • XCAP org.openmobilealliance.pres-content document for serving user icon
  • XCAP pidf-manipulation for offline status
  • XCAP xcap-caps and org.openmobilealliance.xcap-directory for listing all XCAP documents on the server

MSRP Relay

If you use SIMPLE instant messaging based on MSRP, a MSRP relay is available for helping traverse the NAT. You need to use the relay if you are the receiving party and you are behind a NAT-ed router. The MSRP relays can be found in the DNS by using SRV lookup for

STUN Servers

You may use STUN for ICE NAT traversal. The STUN servers can be found in the DNS by using SRV lookup for

NAT Traversal

SIP2SIP infrastructure is smart enough to handle the NAT traversal for both SIP signaling, RTP and MSRP media sessions. Also it supports ICE negotiation in the clients and provides automatically a TURN relay candidate.

Practically, you should not set any NAT traversal features in the client as the chance of fixing things is much smaller than breaking them.