There are many scenarios where inspecting incoming SIP messages for custom headers is useful. Many servers add their custom headers for custom functionalities like custom ring tones, shared line functionality, privacy, etc. and hence having the ability to inspect incoming SIP messages is very useful...

Adding custom SIP headers using RTC, in CE 6.0 R2 release. In CE 6.0 R2, RTC now supports the capability of adding custom headers to outgoing REQUEST messages, for RTC sessions and RTC subscriptions. Here is how once can do it. After CE 6.0 R2 release, IRTCSession interface and IRTCSubscription...

RTC 1.5 can be restricted to use only certain types of interfaces (Wifi, Ethernet, etc.) on Windows Mobile devices. Same restriction cannot be applied on Windows CE, as RTC uses connection manager functionality to do that, which is not available on Windows CE. RTC can be restricted using the following...

RTC 1.5 (CE 6.0 R 2 release) supports Point to Point Video calling. However, the stack does not ship any built-in video codecs. Instead it supports a pluggable video codec architecture through which, one can add their own video codecs. Below are the steps one needs to take to plug-in a video codec...

Sample code for local audio mixing to achieve 3 way/N way calling. In CE 6.0 R2 release, RTC 1.5 started supporting local audio mixing. Local audio mixing can be enabled by using the flag RTCIF_ENABLE_GLOBAL_MEDIA_MIXING during RTCClient object initialization. Here is the code example (ignoring error...

Following are the new features in RTC 6.0 R2 release: 1. Local audio mixing capability (enabling 3 way VOIP calling) 2. Point to Point Video Calls 3. Pluggable Video Codec capability 4. Ability to inspect SIP headers for certain SIP messages 5. Ability to add custom headers to certain outgoing SIP...

This blog explains the different components that contribute to the audio delay in a VOIP call, and then discusses RTC's VOIP delay numbers. When any VOIP call made between any 2 VOIP entities, the end-to-end delay for the VOIP call can be categorized as following: a. VOIP Sender side delay b...

RTC uses standard based SIP signaling and RTP/RTCP media streams to provide VOIP functionality. To verify this, I carried out a little experiment to see if RTC works with existing VOIP services like Vonage. Guess what? It did :). Here are the steps to configure RTC to make it work with Vonage. Please...

There were many queries about using RTC on Windows Mobile platform. With this blog, I will try to clarify on which platforms RTC is available and supported. So far, RTC has always shipped as a part of the general embedded CE release. It is supported as a part of CE releases only. Until WM6, RTC was...

RTC Core Layer and SIP protocol keys Port manager related keys Key Path: HKLM\Comm\\RTC\\PortRange Key Value(s) Key Value Type Description Enabled DWORD Enables Port range as defined by subsequent port key values MinSipDynamicPort...

There has been several documentation errors related to RTC 1.5 on MSDN. Here are a few of them: Issue 1: http://msdn2.microsoft.com/en-us/library/aa924993.aspx The following page mentions that RTC 1.5 supports multi party audio/video and application sessions. This is incorrect. RTC 1.5...

RTC 1.5 supports quality of service for SIP & audio packets using DSCP and 802.1Q tagging. Windows CE has the following pre-defined DSCP traffic types: typedef enum _DSCP_TRAFFIC_TYPE { DSCPTypeNotSet = 0, DSCPBestEffort = 1, DSCPBackground = 2, DSCPExcellentEffort = 3, DSCPVideo = 4, DSCPAudio...

In my first post , I touched on all the new features of RTC 1.5. Prathap also posted a blog on RTC 1.5 port manager, which shows how RTC's port manager APIs can be used by user app to communicate outside NAT. Here I will try to complete the NAT picture of RTC 1.5 As mentioned in my first blog , RTC...

Updates to RTC APIs on CE, has been prolonged for some time and there has been many updates to it and thus a blog to cover some high level overview of changes in RTC 1.5: RTC Overview RTC is mainly used for real time communication mechanisms like IM, Voice over IP and other real time sharing applications...