See: http://www.homephonechoices.co.uk/hpc_summary.asp?pid=443&kt=ns~guk-homephonechoices.co.uk~gtl for details

To get the offer you must go via homephonechoices.

You do of course  pay for the calls and call features you use on top  ;).

But handy if you want a line just for your broadband ,or make few outgoing calls.

Note. I have seen a number of reports suggesting Primus Customer Service is not up to much.

It is a good deal which I have but, yes, Primus customer service is terrible.

Before you decide check out the alternatives at Money Saving Expert http://www.moneysavingexpert.com/utilities/?tab=13

And also have a read of the below thread:

http://forums.moneysavingexpert.com/showthread.php?t=3028460

Fine if you can live without Caller Display, but who can these days?

If you can't, add Primus's extortionate charge of £2.50 a month and it comes to £9.29 per month/£111.48 per annum - not much cheaper than BT's lowest price of £10 a month/£120 per annum (Line Rental Saver), and that includes inclusive weekend calls (unlike Primus's £6.79 deal), as well as inclusive Caller Display.

If you want Caller Display at no extra cost, I believe BT is still the cheapest option. (Worst luck. I hate BT and the way they operate.)

Primus's £7.99 a month deal (also via Homephone Choices) is better than their £6.79 one. It includes Evening and Weekend calls (post-6pm, not 7pm as with BT now), and with the £2.50 Caller Display charge comes to £10.49 per month/£125.88 per annum - not a great deal more than BT's cheapest Line Rental Saver tariff.