Beeline is the mobile operator I have used since 2012 as a pay-as-you-go (PAYG) and find it works just fine in most areas of Kazakhstan (the NE, far east and SE) I travel in.
I mainly use it for SMS and occasional calls (both inside Kazakhstan and to Australia) but only use data vary rarely (if there is in-home internet or power failure) so my spend is quite low, perhaps topping up to KZT20 000 every few months.
Be warned, if you travel to Kyrgyzstan (and other countries), it is best to get a local SIM, because the cost of roaming can be quite high if you are on PAYG, KZT2 000 for a couple of minutes.
The parent company of KCell is another big mobile supplier here, but there was news recently that they are exiting Kazakhstan ...
Landline is one of the lesser used communication methods here, perhaps as a legacy of the CCCP-era where not all people had landlines.
This has meant that take-up of mobile 'phones and fibre-optic internet (in particular) was very quick here in comparison to many western nations because there was no large alternative legacy copper-wire infrastructure to compete with.
Even here out on the far eastern edge of Kazakhstan in Ust-Kamenogorsk, most places are connected with fibre-optic cabling for both internet and TV.