By Katie Marsal

Published: 10:00 AM EST

Apple could announce sales of more than 4 million 3G iPhones at its media event next week, according to investment bank RBC Capital Markets, which also suggests the company may be looking into a low cost "iPod phone" to build on its momentum.

Analyst Mike Abramsky made the comments in a research note Wednesday, saying "resilient post-launch" sell-through has paced the company ahead of Wall Street's expectations and on target with his forecast of 5.1 million 3G units in the September quarter and 14 million total iPhone units for the calendar year.

Apple plans to hold a media event next Tuesday to usher in a refreshed line of iPod digital music players and unveil new iTunes services, but may also use the forum to provide an update on iPhone 3G sales, Abramsky said. He added that the Cupertino-based company has also promised by September a new version of iPhone Software (v2.1) with system-wide push notification support and improved GPS tracking, which may also make an appearance.

The analyst also used his report to toss around the prospect of a completely new device that could be brewing at Apple, but one that he does not expect at Tuesday's event. Though unsupported by any hard evidence, Abramsky said he has reason to believe the electronics maker is exploring the possibility of an "entry level, low cost (less than $99 subsidized) prepaid iPod/phone" that would be restricted to music playback and voice calls.

Such a device would allow the company to "capture an untapped global opportunity," he said. Marketing the pre-paid handset through retail outlets worldwide would provide a residual effect that would both "boost iPhone's momentum by 50 to 100 percent" while establishing future iPhone upgrades and enhanced global Mac sales.

As is the case for the iPhone 3G, the current quarter is proving to be yet another breakout period for Mac sales. Abramsky, who previously published the most bullish known estimates for Mac sales at 3.04 million units, said he stands by that forecast, which continues to see support from his firm's proprietary data.

He sees refreshed MacBooks and MacBook Pros with "aluminum enclosures, larger multi-touch trackpads, and updated specs" arriving sometime after next week's iPod event. He also expects Apple's global PC market share to rise to 4.2 percent by next year, up from 2.9 percent in 2007.

Abramsky maintains an Outperform rating on Apple shares.