While Google's Android OS promises to break open the mobile market, some insiders are wondering why it has no support for SIP or IMS. How revolutionary can Android be if it does not include SIP?

Here is a look at one blogger's take on the issue:

One of the questions I asked was: Android has no SIP stack. It also has no IMS stack/interface to speak of either. What are the implications of that?

This is interesting .. It may be a gap for a start-up. Or .. It may be irrelevant – here is why ..

Basically IMS is a secure mobile connection and / or a guaranteed (QOS) mobile connection. By working at the service layer, Google overcomes some of the issues that hamper IMS type applications. In doing so, it foregoes certain applications(potentially things requiring some form of higher QOS.).

However, if the bearer is WiFi (as it is starting to be increasingly) then this does not matter because many network /telephony applications can be run over WiFi. Downside is low QOS.

I don't share this blogger's tepid reaction. I think the fact that Android doesn't include either SIP or IMS is telling. While Android is pushing itself as the Linux-based open standard for mobility, the search giant is intentionally avoiding two other standards. SIP has long promised to create easy-to-use telephony applications. But SIP's potential has yet to be realized. As for IMS, the standard promises one platform for all carrier-grade access -- both wireless and wireline. But frankly, IMS is beginning to feel like the other side of SIP, another unrealized horn of hype.

I can think of three reasons why Google avoided putting a SIP and/or IMS stack in Android. Reason one is simple: Google thinks these technologies aren't yet ready for primetime and will support them once they gain traction.

Yuck, that felt like typing a canned PR line. Now let's dive into the other two reasons.

The next reason could be that Google thinks SIP and IMS are irrelevant to mobility. And right now, that's an accurate position. Neither carriers nor handset makers are really pushing these standards on these devices and consumers still don't seem that interested in SIP-based applications.

But, if both SIP and IMS are irrelevant today, that could mean they remain irrelevant forever. Which leads me to reason three.

Maybe Google wants to replace SIP and IMS -- or subsume them within Android. By leaving these standards out, Google can position Android as the default platform for mobile devices and once it gets its fingers around the carriers from the device side, it can then take over the ecosystems for SIP and IMS and move the service providers onto these systems -- or whatever technology Google positions in their place.

What do you think? Why didn't Google include SIP and IMS stacks in Android?