Limit alerts to 144 characters?

Hello, we get our nagios alerts sent by email and also via bulksms. Unfortunately we’ve noticed that some of the alerts get silently dropped.
It seems we’re hitting some sort of character limit for texts.
I’ve tried limiting the amount of information that is sent but some things, for example windows memory alerts, don’t like it and either send the whole thing or refuse to monitor anything useful.

This is what we have in our notify by sms command, is there any way to globally limit it and tell it to send only 144 characters?

command_line lynx 'http://www.bulksms.co.uk/eapi/submission/send_sms/2/2.0?username=user&password=pass&msisdn=$CONTACTPAGER$&message=+$NOTIFICATIONTYPE$+$HOSTNAME$+$HOSTADDRESS$.+$HOSTSTATE$

pipe the SMS output through a “head -c 144” before sending it out