A Tiscali spokesman said that the company has now made a number of representations to Ofcom, and that other ISPs are equally unhappy about BT's slow release of access to its exchanges.
But BT has hit back at the accusation that it is delaying the roll-out of IPTV services that rival its own BT Vision, which launched last month.
BT said: 'We have received no complaints in relation to installing Tiscali equipment at BT exchanges, either directly or via Ofcom. Tiscali is enjoying the same fair and equal access to BT exchanges as the rest of the telecoms industry.'
A BT spokesman added that the telco has enabled hundreds of exchanges for Tiscali.
The dispute comes after Tiscali launched an extended pilot of its Homechoice IPTV service, rebranded as Tiscali TV. The service is now available to customers at 32 selected London exchanges, each of which can cover several hundred people.
Customers receive more than 80 linear TV channels and over 6,000 hours of VoD programming, including 1,000 movies, complete series such as Spooksand Sex and the City, and a Bafta award-winning library of more than 5,000 music videos. In addition, an on-demand catch-up feature includes prime-time BBC shows from the previous seven days, available to watch at no extra cost.
The launch of Tiscali TV comes five months after Italian internet giant Tiscali paid £60 million for Stevenage-based IPTV pioneer Homechoice. Tiscali is the third-largest DSL broadband provider in the UK market, with 1.7m customers.