I can confirm that the ATRPMS version of Asterisk breaks Zaptel.
Well, yes & no. We have Asterisk 1.4.22 running quite happily with Dahdi/zaptel on one of our machines here. However, we did have to make a few changes. so... for a very short period (and we mean very short) you can pull the 1.4.21 rpms from here...
http://sarkpbx.com/sail/kmdls/asterisk-1.4.21-Kernel-2.6.9-78.0.8Now, we really are quite limited on bandwidth so down't download this stuff 'just because you can'. If it gets overloaded we will just shut it down. If you have some spare bandwidth then by all means grab the lot and post on here where people can download from.
-715 will be the last planned zaptel release of sail (there may be a few bugfixes, but that's all). We have loosely scheduled -720 as the first DAHDI release. It will run with 2.6.9-78.0.13 kernel (which you can yum update to now - although you may get shouted at by the SME elders - we don't know what the official update line is). The SARK .iso will be zaptel/asterisk 1.4.21 as planned.
S