Apple CEO Steve Jobs plans a conference call tomorrow to discuss the first anniversary of iTunes Music Store.

The call isn't open to the public and at this point it's unclear if it will be streamed at a later juncture. It takes place 8.30am (PDT), that's 4.30pm in the UK.

While it's not certain what will be discussed during the call, certain critical questions are likely to be voiced.

Apple has announced its intent to launch a similar service in Europe this year, though recent reports indicate the start of this has been delayed, due to the complexity of licensing and rights negotiations in the territory.

The company's continued success with its iPods is a potential candidate for discussion, as is the forthcoming global launch of an HP-branded iPod in July.

It appears possible that Jobs will discuss the number of songs sold through the service in its first year. In March Apple revealed it to have sold in excess of 50 million tracks so far. Jobs had set Apple a target figure of 100 million song sales in the first year.

Format incompatibility between digital music services is also a candidate for discussion – Apple exploits an adapted form of AAC (boosted with proprietary rights-management systems) for its service, while competing services and devices use Windows Media 9, which isn't supported by iPods, for example.

Critics say Apple's refusal to license its rights-management systems will eventually hinder take-up of online music stores. Jobs does not agree, saying that licensing the technology "makes no business sense".

He said this when discussing Apple's decision to spurn an overture from RealNetworks that requested an alliance to help see off competition from Microsoft technology-backed services.

Finally, a number of digital entertainment devices are rumoured to be in development at Apple, but no hard evidence of this has yet been obtained.